U.S. patent number 11,368,723 [Application Number 17/072,980] was granted by the patent office on 2022-06-21 for signaling of coding tools for encoding a video component as monochrome video.
This patent grant is currently assigned to Tencent America LLC. The grantee listed for this patent is Tencent America LLC. Invention is credited to Cheung Auyeung, Xiang Li, Shan Liu.
United States Patent |
11,368,723 |
Auyeung , et al. |
June 21, 2022 |
Signaling of coding tools for encoding a video component as
monochrome video
Abstract
A method of video decoding performed in a video decoder is
disclosed. A syntax element can be received from a bitstream of a
coded video that indicates whether a sequence of pictures are
monochrome or include three color components that are coded
separately. By inferring a value of a syntax element, a coding tool
can be disabled when the syntax element indicates that the sequence
of pictures are monochrome or include three color components that
are coded separately. The coding tool uses multiple color
components of a picture as input or depends on a chroma component
of a picture. Examples of the disabled coding tools can include
joint coding of chroma residuals, active color transform (ACT), or
block-based delta pulse code modulation (BDPCM) for chroma
component.
Inventors: |
Auyeung; Cheung (Sunnyvale,
CA), Li; Xiang (Saratoga, CA), Liu; Shan (San Jose,
CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Tencent America LLC |
Palo Alto |
CA |
US |
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Assignee: |
Tencent America LLC (Palo Alto,
CA)
|
Family
ID: |
1000006385373 |
Appl.
No.: |
17/072,980 |
Filed: |
October 16, 2020 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20210120272 A1 |
Apr 22, 2021 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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62924674 |
Oct 22, 2019 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04N
19/186 (20141101); H04N 19/176 (20141101); H04N
19/70 (20141101) |
Current International
Class: |
H04N
19/70 (20140101); H04N 19/176 (20140101); H04N
19/186 (20140101); H04N 19/44 (20140101); H04N
19/60 (20140101) |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
International Search Report and Written Opinion dated Jan. 21, 2021
in International Application No. PCT/US20/56275, (15 pgs.). cited
by applicant .
Description of Core Experiments on Compression of neural networks
for multimedia content description and analysis, ISO/IEC JTC 1/SC
29/WG 11/N18782, Oct. 2019, Geneva, CH, , Coding of moving pictures
and audio, Covenorship; UNI (Italy, 14 pgs. cited by applicant
.
Working Draft 2 of Compression of neural networks for multimedia
content description and analysis, ISO/IEC JTC 1/SC 29/WG 11/18784,
Oct. 2019, Geneva CH, Coding of moving pictures and audio,
Covenorship: UNI (Italy), 26 pgs. cited by applicant .
Test model 2 of Compression of neural networks for multimedia
content description and analysis, ISO/IEC JTC 1/SC 29/WG 11/N18785,
Oct. 2019, Geneva, CH, Coding of moving pictures and audio,
Covenorship: UNI (Italy), 10 pgs. cited by applicant .
"Series H: Audiovisual and Multimedia Systems Infrastructure of
audiovisual services--Coding of moving video, High efficiency video
coding", ITU-T Telecommunication Standardization Sector of ITU
(International Telecommunication Union), H.265 (Dec. 2016) (664
pages). cited by applicant .
Bross et al., "Versatile Video Coding (Draft 7)", Joint Video
Experts Team (JVET) of ITU-T SG 16 WP 3 and ISO/IEC JTC 1/SC 29/WG
11, 16th Meeting: Geneva, CH, Oct. 1-11, 2019, Document:
JVET-P2001-vA (486 pages). cited by applicant .
Chen et al., "Algorithm description for Versatile Video Coding and
Test Model 6 (VTM 6)", Joint Video Experts Team (JVET) of ITU-T SG
16 WP 3 and ISO/IEC JTC 1/SC 29/WG 11, 15th Meeting: Gothenburg,
SE, Jul. 3-12, 2019, Document: JVET-O2002-v2 (87 pages). cited by
applicant.
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Primary Examiner: Braniff; Christopher
Attorney, Agent or Firm: ArentFox Schiff LLP
Parent Case Text
INCORPORATION BY REFERENCE
This present disclosure claims the benefit of priority to U.S.
Provisional Application No. 62/924,674, "Signaling of Video Coding
Tools for the Encoding of a Video Component as Monochrome Video"
filed on Oct. 22, 2019, which is incorporated by reference herein
in its entirety.
Claims
What is claimed is:
1. A method of video decoding performed in a video decoder,
comprising: receiving a first syntax element from a bitstream of a
coded video, the first syntax element indicating whether a sequence
of pictures are monochrome or include three color components that
are coded separately; and inferring a value of a second syntax
element to disable a first coding tool that uses multiple color
components of a picture as input or depends on a chroma component
of a picture in response to the first syntax element indicating
that the sequence of pictures are monochrome or include three color
components that are coded separately, the first syntax element and
the second syntax element being different syntax elements, wherein
the second syntax element indicates whether joint coding of chroma
residuals is enabled.
2. The method of claim 1, wherein the inferring the value of the
second syntax element to disable the first coding tool that uses
the multiple color components of the picture as input includes:
inferring the value of the second syntax element indicates that the
joint coding of chroma residuals is disabled.
3. The method of claim 1, further comprising: inferring a value of
a third syntax element to disable a second coding tool that uses
multiple color components of the picture as input, wherein the
third syntax element indicates whether active color transform (ACT)
is enabled, and the value of the third syntax element is inferred
to be equal to zero.
4. The method of claim 1, further comprising: inferring a value of
a fourth syntax element to disable a third coding tool that depends
on a chroma component of the picture as input, wherein the fourth
syntax element indicates whether block-based delta pulse code
modulation (BDPCM) for chroma component is enabled, and the value
of the fourth syntax element is inferred to be equal to zero.
5. The method of claim 1, wherein the inferring the value of the
second syntax element to disable the first coding tool that uses
the multiple color components of the picture as input or depends on
the chroma component of the picture includes: determining a value
of a variable to be zero when the first syntax element indicates
that the sequence of pictures are monochrome or include three color
components that are coded separately, the variable indicating a
chroma array type of the sequence of pictures; and in response to
determining the value of the variable to be zero, inferring the
value of one of the following syntax elements to be equal to zero:
the second syntax element indicating whether the joint coding of
chroma residuals is enabled, a third syntax element indicating
whether ACT is enabled, or a fourth syntax element indicating
whether BDPCM for chroma component is enabled.
6. The method of claim 1, further comprising: receiving the second
syntax element indicating whether the joint coding of chroma
residuals is enabled when the sequence of pictures are determined
as not monochrome and include three color components that are not
coded separately.
7. The method of claim 3, further comprising: receiving the third
syntax element indicating whether the ACT is enabled when the
sequence of pictures are determined as not monochrome and include
three color components that are not coded separately.
8. The method of claim 4, further comprising: receiving the fourth
syntax element indicating whether the BDPCM for chroma component is
enabled when the sequence of pictures are determined as not
monochrome and include three color components that are not coded
separately.
9. The method of claim 1, further comprising: determining a value
of a variable indicating a chroma array type of the sequence of
pictures when the sequence of pictures are determined as not
monochrome and include three color components that are not coded
separately; and receiving one of the following syntax elements when
the value of the variable is determined to be non-zero: the second
syntax element indicating whether the joint coding of chroma
residuals is enabled, a third syntax element indicating whether ACT
is enabled, or a fourth syntax element indicating whether BDPCM for
chroma component is enabled.
10. The method of claim 1, further comprising: determining a value
of a variable indicating a chroma array type of the sequence of
pictures when the sequence of pictures are determined as not
monochrome and include three color components that are not coded
separately; and receiving a syntax element indicating whether BDPCM
for chroma component is enabled when the value of the variable is
determined to be non-zero, and when a lossless mode is enabled for
the sequence of pictures.
11. An apparatus of video decoding, comprising circuitry configured
to: receive a first syntax element from a bitstream of a coded
video, the first syntax element indicating whether a sequence of
pictures are monochrome or include three color components that are
coded separately; and infer a value of a second syntax element to
disable a first coding tool that uses multiple color components of
a picture as input or depends on a chroma component of a picture in
response to the first syntax element indicating that the sequence
of pictures are monochrome or include three color components that
are coded separately, the first syntax element and the second
syntax element being different syntax elements, wherein the second
syntax element indicates whether joint coding of chroma residuals
is enabled.
12. The apparatus of claim 11, wherein the circuitry is further
configured to: infer the value of the second syntax element
indicates that joint coding of chroma residuals is disabled.
13. The apparatus of claim 11, wherein the circuitry is further
configured to: infer a value of a third syntax element to be equal
to zero to disable a second coding tool that uses multiple color
components of the picture as input, the third syntax element
indicating whether active color transform (ACT) is enabled.
14. The apparatus of claim 11, wherein the circuitry is further
configured to: infer a value of a fourth syntax element to be equal
to zero to disable a third coding tool that depends on a chroma
component of the picture as input, the fourth syntax element
indicating whether block-based delta pulse code modulation (BDPCM)
for chroma component is enabled.
15. A non-transitory computer-readable medium storing instructions
that, when executed by a processor, cause the processor to perform
a method of video decoding, the method comprising: Receiving a
first syntax element from a bitstream of a coded video, the first
syntax element indicating whether a sequence of pictures are
monochrome or include three color components that are coded
separately; and inferring a value of a second syntax element to
disable a first coding tool that uses multiple color components of
a picture as input or depends on a chroma component of a picture in
response to the first syntax element indicating that the sequence
of pictures are monochrome or include three color components that
are coded separately, the first syntax element and the second
syntax element being different syntax elements, wherein the second
syntax element indicates whether joint coding of chroma residuals
is enabled.
16. The non-transitory computer-readable medium of claim 15,
wherein the inferring the value of the second syntax element to
disable the first coding tool that uses the multiple color
components of the picture as input includes: inferring the value of
the second syntax element indicates that the joint coding of chroma
residuals is disabled.
17. The non-transitory computer-readable medium of claim 15,
wherein the method further includes: inferring a value of a third
syntax element to be equal to zero to disable a second coding tool
that uses multiple color components of the picture as input, the
third syntax element indicating whether active color transform
(ACT) is enabled.
Description
TECHNICAL FIELD
The present disclosure describes embodiments generally related to
video coding.
BACKGROUND
The background description provided herein is for the purpose of
generally presenting the context of the disclosure. Work of the
presently named inventors, to the extent the work is described in
this background section, as well as aspects of the description that
may not otherwise qualify as prior art at the time of filing, are
neither expressly nor impliedly admitted as prior art against the
present disclosure.
Video coding and decoding can be performed using inter-picture
prediction with motion compensation. Uncompressed digital video can
include a series of pictures, each picture having a spatial
dimension of, for example, 1920.times.1080 luminance samples and
associated chrominance samples. The series of pictures can have a
fixed or variable picture rate (informally also known as frame
rate), of, for example 60 pictures per second or 60 Hz.
Uncompressed video has significant bitrate requirements. For
example, 1080p60 4:2:0 video at 8 bit per sample (1920x1080
luminance sample resolution at 60 Hz frame rate) requires close to
1.5 Gbit/s bandwidth. An hour of such video requires more than 600
GBytes of storage space.
One purpose of video coding and decoding can be the reduction of
redundancy in the input video signal, through compression.
Compression can help reduce the aforementioned bandwidth or storage
space requirements, in some cases by two orders of magnitude or
more. Both lossless and lossy compression, as well as a combination
thereof can be employed. Lossless compression refers to techniques
where an exact copy of the original signal can be reconstructed
from the compressed original signal. When using lossy compression,
the reconstructed signal may not be identical to the original
signal, but the distortion between original and reconstructed
signals is small enough to make the reconstructed signal useful for
the intended application. In the case of video, lossy compression
is widely employed. The amount of distortion tolerated depends on
the application; for example, users of certain consumer streaming
applications may tolerate higher distortion than users of
television distribution applications. The compression ratio
achievable can reflect that: higher allowable/tolerable distortion
can yield higher compression ratios.
A video encoder and decoder can utilize techniques from several
broad categories, including, for example, motion compensation,
transform, quantization, and entropy coding.
Video codec technologies can include techniques known as intra
coding. In intra coding, sample values are represented without
reference to samples or other data from previously reconstructed
reference pictures. In some video codecs, the picture is spatially
subdivided into blocks of samples. When all blocks of samples are
coded in intra mode, that picture can be an intra picture. Intra
pictures and their derivations such as independent decoder refresh
pictures, can be used to reset the decoder state and can,
therefore, be used as the first picture in a coded video bitstream
and a video session, or as a still image. The samples of an intra
block can be exposed to a transform, and the transform coefficients
can be quantized before entropy coding. Intra prediction can be a
technique that minimizes sample values in the pre-transform domain.
In some cases, the smaller the DC value after a transform is, and
the smaller the AC coefficients are, the fewer the bits that are
required at a given quantization step size to represent the block
after entropy coding.
Traditional intra coding such as known from, for example MPEG-2
generation coding technologies, does not use intra prediction
besides DC prediction. However, some newer video compression
technologies include techniques that attempt, from, for example,
surrounding sample data and/or metadata obtained during the
encoding/decoding of spatially neighboring, and preceding in
decoding order, blocks of data. Such techniques are henceforth
called "intra prediction" techniques. Note that in at least some
cases, intra prediction is only using reference data from the
current picture under reconstruction and not from reference
pictures.
There can be many different forms of intra prediction. When more
than one of such techniques can be used in a given video coding
technology, the technique in use can be coded in an intra
prediction mode. In certain cases, modes can have submodes and/or
parameters, and those can be coded individually or included in the
mode codeword. Which codeword to use for a given
mode/submode/parameter combination can have an impact in the coding
efficiency gain through intra prediction, and so can the entropy
coding technology used to translate the codewords into a
bitstream.
A certain mode of intra prediction was introduced with H.264,
refined in H.265, and further refined in newer coding technologies
such as joint exploration model (JEM), versatile video coding
(VVC), and benchmark set (BMS). A predictor block can be formed
using neighboring sample values belonging to already available
samples. Sample values of neighboring samples are copied into the
predictor block according to a direction. A reference to the
direction in use can be coded in the bitstream or may itself be
predicted.
Referring to FIG. 1A, depicted in the lower right is a subset of
nine predictor directions known from H.265's 33 possible predictor
directions (corresponding to the 33 angular modes of the 35 intra
modes). The point where the arrows converge (101) represents the
sample being predicted. The arrows represent the direction from
which the sample is being predicted. For example, arrow (102)
indicates that sample (101) is predicted from a sample or samples
to the upper right, at a 45 degree angle from the horizontal.
Similarly, arrow (103) indicates that sample (101) is predicted
from a sample or samples to the lower left of sample (101), in a
22.5 degree angle from the horizontal.
Still referring to FIG. 1A, on the top left there is depicted a
square block (104) of 4.times.4 samples (indicated by a dashed,
boldface line). The square block (104) includes 16 samples, each
labelled with an "S", its position in the Y dimension (e.g., row
index) and its position in the X dimension (e.g., column index).
For example, sample S21 is the second sample in the Y dimension
(from the top) and the first (from the left) sample in the X
dimension. Similarly, sample S44 is the fourth sample in block
(104) in both the Y and X dimensions. As the block is 4.times.4
samples in size, S44 is at the bottom right. Further shown are
reference samples that follow a similar numbering scheme. A
reference sample is labelled with an R, its Y position (e.g., row
index) and X position (column index) relative to block (104). In
both H.264 and H.265, prediction samples neighbor the block under
reconstruction; therefore no negative values need to be used.
Intra picture prediction can work by copying reference sample
values from the neighboring samples as appropriated by the signaled
prediction direction. For example, assume the coded video bitstream
includes signaling that, for this block, indicates a prediction
direction consistent with arrow (102)--that is, samples are
predicted from a prediction sample or samples to the upper right,
at a 45 degree angle from the horizontal. In that case, samples
S41, S32, S23, and S14 are predicted from the same reference sample
R05. Sample S44 is then predicted from reference sample R08.
In certain cases, the values of multiple reference samples may be
combined, for example through interpolation, in order to calculate
a reference sample; especially when the directions are not evenly
divisible by 45 degrees.
The number of possible directions has increased as video coding
technology has developed. In H.264 (year 2003), nine different
direction could be represented. That increased to 33 in H.265 (year
2013), and JEM/VVC/BMS, at the time of disclosure, can support up
to 65 directions. Experiments have been conducted to identify the
most likely directions, and certain techniques in the entropy
coding are used to represent those likely directions in a small
number of bits, accepting a certain penalty for less likely
directions. Further, the directions themselves can sometimes be
predicted from neighboring directions used in neighboring, already
decoded, blocks.
The intra prediction modes used in HEVC are illustrated in FIG. 1B.
In HEVC, there are total 35 intra prediction modes, among which
mode 10 is horizontal mode, mode 26 is vertical mode, and mode 2,
mode 18 and mode 34 are diagonal modes. The intra prediction modes
are signalled by three most probable modes (MPMs) and 32 remaining
modes.
FIG. 1C illustrates the intra prediction modes used in VVC. In VVC,
there are total 95 intra prediction modes as shown in FIG. 1C,
where mode 18 is the horizontal mode, mode 50 is the vertical mode,
and mode 2, mode 34 and mode 66 are diagonal modes. Modes
-1.about.-14 and Modes 67.about.80 are called Wide-Angle Intra
Prediction (WAIP) modes.
The mapping of intra prediction directions bits in the coded video
bitstream that represent the direction can be different from video
coding technology to video coding technology; and can range, for
example, from simple direct mappings of prediction direction to
intra prediction mode, to codewords, to complex adaptive schemes
involving MPMs, and similar techniques. In all cases, however,
there can be certain directions that are statistically less likely
to occur in video content than certain other directions. As the
goal of video compression is the reduction of redundancy, those
less likely directions will, in a well working video coding
technology, be represented by a larger number of bits than more
likely directions.
Video coding and decoding can be performed using inter-picture
prediction with motion compensation. Uncompressed digital video can
include a series of pictures, each picture having a spatial
dimension of, for example, 1920.times.1080 luminance samples and
associated chrominance samples. The series of pictures can have a
fixed or variable picture rate (informally also known as frame
rate) of, for example 60 pictures per second or 60 Hz. Uncompressed
video has significant bitrate requirements. For example, 1080p60
4:2:0 video at 8 bit per sample (1920x1080 luminance sample
resolution at 60 Hz frame rate) requires close to 1.5 Gbit/s
bandwidth. An hour of such video requires more than 600 GBytes of
storage space.
Motion compensation can be a lossy compression technique and can
relate to techniques where a block of sample data from a previously
reconstructed picture or part thereof (reference picture), after
being spatially shifted in a direction indicated by a motion vector
(MV henceforth), is used for the prediction of a newly
reconstructed picture or picture part. In some cases, the reference
picture can be the same as the picture currently under
reconstruction. MVs can have two dimensions X and Y, or three
dimensions, the third being an indication of the reference picture
in use (the latter, indirectly, can be a time dimension).
In some video compression techniques, an MV applicable to a certain
area of sample data can be predicted from other MVs, for example
from those related to another area of sample data spatially
adjacent to the area under reconstruction, and preceding that MV in
decoding order. Doing so can substantially reduce the amount of
data required for coding the MV, thereby removing redundancy and
increasing compression. MV prediction can work effectively, for
example, because when coding an input video signal derived from a
camera (known as natural video) there is a statistical likelihood
that areas larger than the area to which a single MV is applicable
move in a similar direction and, therefore, can in some cases be
predicted using a similar motion vector derived from MVs of
neighboring area. That results in the MV found for a given area to
be similar or the same as the MV predicted from the surrounding
MVs, and that in turn can be represented, after entropy coding, in
a smaller number of bits than what would be used if coding the MV
directly. In some cases, MV prediction can be an example of
lossless compression of a signal (namely: the MVs) derived from the
original signal (namely: the sample stream). In other cases, MV
prediction itself can be lossy, for example because of rounding
errors when calculating a predictor from several surrounding
MVs.
Various MV prediction mechanisms are described in H.265/HEVC (ITU-T
Rec. H.265, "High Efficiency Video Coding", December 2016). Out of
the many MV prediction mechanisms that H.265 offers, described here
is a technique henceforth referred to as "spatial merge".
Referring to FIG. 1D, a current block (110) comprises samples that
have been found by the encoder during the motion search process to
be predictable from a previous block of the same size that has been
spatially shifted. Instead of coding that MV directly, the MV can
be derived from metadata associated with one or more reference
pictures, for example from the most recent (in decoding order)
reference picture, using the MV associated with either one of five
surrounding samples, denoted A0, A1, and B0, B1, B2 (102 through
106, respectively). In H.265, the MV prediction can use predictors
from the same reference picture that the neighboring block is
using. The order of forming a candidate list may be
A0.fwdarw.B0.fwdarw.B1.fwdarw.A1.fwdarw.B2.
SUMMARY
Aspects of the disclosure provide a method of video decoding
performed in a video decoder. A syntax element can be received from
a bitstream of a coded video that indicates whether a sequence of
pictures are monochrome or include three color components that are
coded separately. By inferring a value of a syntax element, a
coding tool can be disabled when the syntax element indicates that
the sequence of pictures are monochrome or include three color
components that are coded separately. The coding tool uses multiple
color components of a picture as input or depends on a chroma
component of a picture.
In an embodiment, the disabled coding tool is one of a coding tool
of joint coding of chroma residuals, active color transform (ACT),
or block-based delta pulse code modulation (BDPCM) for chroma
component.
In an embodiment, the value of the syntax element indicating
whether joint coding of chroma residuals is enabled is inferred to
be equal to zero. In an embodiment, the value of the syntax element
indicating whether ACT is enabled can be inferred to be equal to
zero. In an embodiment, the value of the syntax element indicating
whether BDPCM for chroma component is enabled can be inferred to be
equal to zero.
In an embodiment, a value of a variable is determined to be zero
when the syntax element indicates that the sequence of pictures are
monochrome or include three color components that are coded
separately. The variable indicates a chroma array type of the
sequence of pictures. In response to determining the value of the
variable to be zero, the value of one of the following syntax
elements can inferred to be equal to zero: a syntax element
indicating whether joint coding of chroma residuals is enabled, a
syntax element indicating whether ACT is enabled, or a syntax
element indicating whether BDPCM for chroma component is
enabled.
In some embodiments, in response to determining the sequence of
pictures are not monochrome and include three color components that
are not coded separately, a syntax element indicating whether joint
coding of chroma residuals is enabled can be received; a syntax
element indicating whether ACT is enabled can be received; or a
syntax element indicating whether BDPCM for chroma component is
enabled can be received.
In an embodiment, in response to determining the sequence of
pictures are not monochrome and include three color components that
are not coded separately, a value of a variable indicating a chroma
array type of the sequence of pictures can be determined. One of
the following syntax elements can be received when the value of the
variable is determined to be non-zero: a syntax element indicating
whether joint coding of chroma residuals is enabled, a syntax
element indicating whether ACT is enabled, or a syntax element
indicating whether BDPCM for chroma component is enabled.
In an embodiment, a value of a variable indicating a chroma array
type of the sequence of pictures can be determined when it is
determined that the sequence of pictures are not monochrome and
include three color components that are not coded separately. A
syntax element indicating whether BDPCM for chroma component is
enabled can be received when the value of the variable is
determined to be non-zero, and when a lossless mode is enabled for
the sequence of pictures.
Aspects of the disclosure provide an apparatus of video decoding
comprising circuitry. The circuitry can be configured to receive a
syntax element from a bitstream of a coded video. The syntax
element indicates whether a sequence of pictures are monochrome or
include three color components that are coded separately. The
circuitry can be further configured to infer a value of a syntax
element to disable a coding tool that uses multiple color
components of a picture as input or depends on a chroma component
of a picture when the syntax element indicates that the sequence of
pictures are monochrome or include three color components that are
coded separately.
Aspects of the disclosure provide a non-transitory
computer-readable medium storing instructions that, when executed
by a processor, cause the processor to perform the method of video
decoding.
BRIEF DESCRIPTION OF THE DRAWINGS
Further features, the nature, and various advantages of the
disclosed subject matter will be more apparent from the following
detailed description and the accompanying drawings in which:
FIG. 1A is a schematic illustration of an exemplary subset of intra
prediction modes;
FIG. 1B is an illustration of exemplary intra prediction
directions.
FIG. 1C is an illustration of exemplary intra prediction
directions.
FIG. 1D is a schematic illustration of a current block and its
surrounding spatial merge candidates in one example.
FIG. 2 is a schematic illustration of a simplified block diagram of
a communication system in accordance with an embodiment.
FIG. 3 is a schematic illustration of a simplified block diagram of
a communication system in accordance with an embodiment.
FIG. 4 is a schematic illustration of a simplified block diagram of
a decoder in accordance with an embodiment.
FIG. 5 is a schematic illustration of a simplified block diagram of
an encoder in accordance with an embodiment.
FIG. 6 shows a block diagram of an encoder in accordance with
another embodiment.
FIG. 7 shows a block diagram of a decoder in accordance with
another embodiment.
FIG. 8 is an illustration of an embodiment of a process performed
by a decoder.
FIG. 9 is an illustration of an embodiment of another process
performed by a decoder.
FIG. 10 is a schematic illustration of a computer system in
accordance with an embodiment of the present disclosure.
DETAILED DESCRIPTION OF EMBODIMENTS
I. Video Encoder and Decoder Systems
FIG. 2 illustrates a simplified block diagram of a communication
system (200) according to an embodiment of the present disclosure.
The communication system (200) includes a plurality of terminal
devices that can communicate with each other, via, for example, a
network (250). For example, the communication system (200) includes
a first pair of terminal devices (210) and (220) interconnected via
the network (250). In the FIG. 2 example, the first pair of
terminal devices (210) and (220) performs unidirectional
transmission of data. For example, the terminal device (210) may
code video data (e.g., a stream of video pictures that are captured
by the terminal device (210)) for transmission to the other
terminal device (220) via the network (250). The encoded video data
can be transmitted in the form of one or more coded video
bitstreams. The terminal device (220) may receive the coded video
data from the network (250), decode the coded video data to recover
the video pictures and display video pictures according to the
recovered video data. Unidirectional data transmission may be
common in media serving applications and the like.
In another example, the communication system (200) includes a
second pair of terminal devices (230) and (240) that performs
bidirectional transmission of coded video data that may occur, for
example, during videoconferencing. For bidirectional transmission
of data, in an example, each terminal device of the terminal
devices (230) and (240) may code video data (e.g., a stream of
video pictures that are captured by the terminal device) for
transmission to the other terminal device of the terminal devices
(230) and (240) via the network (250). Each terminal device of the
terminal devices (230) and (240) also may receive the coded video
data transmitted by the other terminal device of the terminal
devices (230) and (240), and may decode the coded video data to
recover the video pictures and may display video pictures at an
accessible display device according to the recovered video
data.
In the FIG. 2 example, the terminal devices (210), (220), (230) and
(240) may be illustrated as servers, personal computers and smart
phones but the principles of the present disclosure may be not so
limited. Embodiments of the present disclosure find application
with laptop computers, tablet computers, media players and/or
dedicated video conferencing equipment. The network (250)
represents any number of networks that convey coded video data
among the terminal devices (210), (220), (230) and (240), including
for example wireline (wired) and/or wireless communication
networks. The communication network (250) may exchange data in
circuit-switched and/or packet-switched channels. Representative
networks include telecommunications networks, local area networks,
wide area networks and/or the Internet. For the purposes of the
present discussion, the architecture and topology of the network
(250) may be immaterial to the operation of the present disclosure
unless explained herein below.
FIG. 3 illustrates, as an example for an application for the
disclosed subject matter, the placement of a video encoder and a
video decoder in a streaming environment. The disclosed subject
matter can be equally applicable to other video enabled
applications, including, for example, video conferencing, digital
TV, storing of compressed video on digital media including CD, DVD,
memory stick and the like, and so on.
A streaming system may include a capture subsystem (313), that can
include a video source (301), for example a digital camera,
creating for example a stream of video pictures (302) that are
uncompressed. In an example, the stream of video pictures (302)
includes samples that are taken by the digital camera. The stream
of video pictures (302), depicted as a bold line to emphasize a
high data volume when compared to encoded video data (304) (or
coded video bitstreams), can be processed by an electronic device
(320) that includes a video encoder (303) coupled to the video
source (301). The video encoder (303) can include hardware,
software, or a combination thereof to enable or implement aspects
of the disclosed subject matter as described in more detail below.
The encoded video data (304) (or encoded video bitstream (304)),
depicted as a thin line to emphasize the lower data volume when
compared to the stream of video pictures (302), can be stored on a
streaming server (305) for future use. One or more streaming client
subsystems, such as client subsystems (306) and (308) in FIG. 3 can
access the streaming server (305) to retrieve copies (307) and
(309) of the encoded video data (304). A client subsystem (306) can
include a video decoder (310), for example, in an electronic device
(330). The video decoder (310) decodes the incoming copy (307) of
the encoded video data and creates an outgoing stream of video
pictures (311) that can be rendered on a display (312) (e.g.,
display screen) or other rendering device (not depicted). In some
streaming systems, the encoded video data (304), (307), and (309)
(e.g., video bitstreams) can be encoded according to certain video
coding/compression standards. Examples of those standards include
ITU-T Recommendation H.265. In an example, a video coding standard
under development is informally known as Versatile Video Coding
(VVC). The disclosed subject matter may be used in the context of
VVC.
It is noted that the electronic devices (320) and (330) can include
other components (not shown). For example, the electronic device
(320) can include a video decoder (not shown) and the electronic
device (330) can include a video encoder (not shown) as well.
FIG. 4 shows a block diagram of a video decoder (410) according to
an embodiment of the present disclosure. The video decoder (410)
can be included in an electronic device (430). The electronic
device (430) can include a receiver (431) (e.g., receiving
circuitry). The video decoder (410) can be used in the place of the
video decoder (310) in the FIG. 3 example.
The receiver (431) may receive one or more coded video sequences to
be decoded by the video decoder (410); in the same or another
embodiment, one coded video sequence at a time, where the decoding
of each coded video sequence is independent from other coded video
sequences. The coded video sequence may be received from a channel
(401), which may be a hardware/software link to a storage device
which stores the encoded video data. The receiver (431) may receive
the encoded video data with other data, for example, coded audio
data and/or ancillary data streams, that may be forwarded to their
respective using entities (not depicted). The receiver (431) may
separate the coded video sequence from the other data. To combat
network jitter, a buffer memory (415) may be coupled in between the
receiver (431) and an entropy decoder/parser (420) ("parser (420)"
henceforth). In certain applications, the buffer memory (415) is
part of the video decoder (410). In others, it can be outside of
the video decoder (410) (not depicted). In still others, there can
be a buffer memory (not depicted) outside of the video decoder
(410), for example to combat network jitter, and in addition
another buffer memory (415) inside the video decoder (410), for
example to handle playout timing. When the receiver (431) is
receiving data from a store/forward device of sufficient bandwidth
and controllability, or from an isosynchronous network, the buffer
memory (415) may not be needed, or can be small. For use on best
effort packet networks such as the Internet, the buffer memory
(415) may be required, can be comparatively large and can be
advantageously of adaptive size, and may at least partially be
implemented in an operating system or similar elements (not
depicted) outside of the video decoder (410).
The video decoder (410) may include the parser (420) to reconstruct
symbols (421) from the coded video sequence. Categories of those
symbols include information used to manage operation of the video
decoder (410), and potentially information to control a rendering
device such as a render device (412) (e.g., a display screen) that
is not an integral part of the electronic device (430) but can be
coupled to the electronic device (430), as was shown in FIG. 4. The
control information for the rendering device(s) may be in the form
of Supplemental Enhancement Information (SEI messages) or Video
Usability Information (VUI) parameter set fragments (not depicted).
The parser (420) may parse/entropy-decode the coded video sequence
that is received. The coding of the coded video sequence can be in
accordance with a video coding technology or standard, and can
follow various principles, including variable length coding,
Huffman coding, arithmetic coding with or without context
sensitivity, and so forth. The parser (420) may extract from the
coded video sequence, a set of subgroup parameters for at least one
of the subgroups of pixels in the video decoder, based upon at
least one parameter corresponding to the group. Subgroups can
include Groups of Pictures (GOPs), pictures, tiles, slices,
macroblocks, Coding Units (CUs), blocks, Transform Units (TUs),
Prediction Units (PUs) and so forth. The parser (420) may also
extract from the coded video sequence information such as transform
coefficients, quantizer parameter values, motion vectors, and so
forth.
The parser (420) may perform an entropy decoding/parsing operation
on the video sequence received from the buffer memory (415), so as
to create symbols (421).
Reconstruction of the symbols (421) can involve multiple different
units depending on the type of the coded video picture or parts
thereof (such as: inter and intra picture, inter and intra block),
and other factors. Which units are involved, and how, can be
controlled by the subgroup control information that was parsed from
the coded video sequence by the parser (420). The flow of such
subgroup control information between the parser (420) and the
multiple units below is not depicted for clarity.
Beyond the functional blocks already mentioned, the video decoder
(410) can be conceptually subdivided into a number of functional
units as described below. In a practical implementation operating
under commercial constraints, many of these units interact closely
with each other and can, at least partly, be integrated into each
other. However, for the purpose of describing the disclosed subject
matter, the conceptual subdivision into the functional units below
is appropriate.
A first unit is the scaler/inverse transform unit (451). The
scaler/inverse transform unit (451) receives a quantized transform
coefficient as well as control information, including which
transform to use, block size, quantization factor, quantization
scaling matrices, etc. as symbol(s) (421) from the parser (420).
The scaler/inverse transform unit (451) can output blocks including
sample values that can be input into aggregator (455).
In some cases, the output samples of the scaler/inverse transform
(451) can pertain to an intra coded block; that is: a block that is
not using predictive information from previously reconstructed
pictures, but can use predictive information from previously
reconstructed parts of the current picture. Such predictive
information can be provided by an intra picture prediction unit
(452). In some cases, the intra picture prediction unit (452)
generates a block of the same size and shape of the block under
reconstruction, using surrounding already reconstructed information
fetched from the current picture buffer (458). The current picture
buffer (458) buffers, for example, partly reconstructed current
picture and/or fully reconstructed current picture. The aggregator
(455), in some cases, adds, on a per sample basis, the prediction
information the intra prediction unit (452) has generated to the
output sample information as provided by the scaler/inverse
transform unit (451).
In other cases, the output samples of the scaler/inverse transform
unit (451) can pertain to an inter coded, and potentially motion
compensated block. In such a case, a motion compensation prediction
unit (453) can access reference picture memory (457) to fetch
samples used for prediction. After motion compensating the fetched
samples in accordance with the symbols (421) pertaining to the
block, these samples can be added by the aggregator (455) to the
output of the scaler/inverse transform unit (451) (in this case
called the residual samples or residual signal) so as to generate
output sample information. The addresses within the reference
picture memory (457) from where the motion compensation prediction
unit (453) fetches prediction samples can be controlled by motion
vectors, available to the motion compensation prediction unit (453)
in the form of symbols (421) that can have, for example X, Y, and
reference picture components. Motion compensation also can include
interpolation of sample values as fetched from the reference
picture memory (457) when sub-sample exact motion vectors are in
use, motion vector prediction mechanisms, and so forth.
The output samples of the aggregator (455) can be subject to
various loop filtering techniques in the loop filter unit (456).
Video compression technologies can include in-loop filter
technologies that are controlled by parameters included in the
coded video sequence (also referred to as coded video bitstream)
and made available to the loop filter unit (456) as symbols (421)
from the parser (420), but can also be responsive to
meta-information obtained during the decoding of previous (in
decoding order) parts of the coded picture or coded video sequence,
as well as responsive to previously reconstructed and loop-filtered
sample values.
The output of the loop filter unit (456) can be a sample stream
that can be output to the render device (412) as well as stored in
the reference picture memory (457) for use in future inter-picture
prediction.
Certain coded pictures, once fully reconstructed, can be used as
reference pictures for future prediction. For example, once a coded
picture corresponding to a current picture is fully reconstructed
and the coded picture has been identified as a reference picture
(by, for example, the parser (420)), the current picture buffer
(458) can become a part of the reference picture memory (457), and
a fresh current picture buffer can be reallocated before commencing
the reconstruction of the following coded picture.
The video decoder (410) may perform decoding operations according
to a predetermined video compression technology in a standard, such
as ITU-T Rec. H.265. The coded video sequence may conform to a
syntax specified by the video compression technology or standard
being used, in the sense that the coded video sequence adheres to
both the syntax of the video compression technology or standard and
the profiles as documented in the video compression technology or
standard. Specifically, a profile can select certain tools as the
only tools available for use under that profile from all the tools
available in the video compression technology or standard. Also
necessary for compliance can be that the complexity of the coded
video sequence is within bounds as defined by the level of the
video compression technology or standard. In some cases, levels
restrict the maximum picture size, maximum frame rate, maximum
reconstruction sample rate (measured in, for example megasamples
per second), maximum reference picture size, and so on. Limits set
by levels can, in some cases, be further restricted through
Hypothetical Reference Decoder (HRD) specifications and metadata
for HRD buffer management signaled in the coded video sequence.
In an embodiment, the receiver (431) may receive additional
(redundant) data with the encoded video. The additional data may be
included as part of the coded video sequence(s). The additional
data may be used by the video decoder (410) to properly decode the
data and/or to more accurately reconstruct the original video data.
Additional data can be in the form of, for example, temporal,
spatial, or signal noise ratio (SNR) enhancement layers, redundant
slices, redundant pictures, forward error correction codes, and so
on.
FIG. 5 shows a block diagram of a video encoder (503) according to
an embodiment of the present disclosure. The video encoder (503) is
included in an electronic device (520). The electronic device (520)
includes a transmitter (540) (e.g., transmitting circuitry). The
video encoder (503) can be used in the place of the video encoder
(303) in the FIG. 3 example.
The video encoder (503) may receive video samples from a video
source (501) (that is not part of the electronic device (520) in
the FIG. 5 example) that may capture video image(s) to be coded by
the video encoder (503). In another example, the video source (501)
is a part of the electronic device (520).
The video source (501) may provide the source video sequence to be
coded by the video encoder (503) in the form of a digital video
sample stream that can be of any suitable bit depth (for example: 8
bit, 10 bit, 12 bit, . . . ), any colorspace (for example, BT.601 Y
CrCB, RGB, . . . ), and any suitable sampling structure (for
example Y CrCb 4:2:0, Y CrCb 4:4:4). In a media serving system, the
video source (501) may be a storage device storing previously
prepared video. In a videoconferencing system, the video source
(501) may be a camera that captures local image information as a
video sequence. Video data may be provided as a plurality of
individual pictures that impart motion when viewed in sequence. The
pictures themselves may be organized as a spatial array of pixels,
wherein each pixel can comprise one or more samples depending on
the sampling structure, color space, etc. in use. A person skilled
in the art can readily understand the relationship between pixels
and samples. The description below focuses on samples.
According to an embodiment, the video encoder (503) may code and
compress the pictures of the source video sequence into a coded
video sequence (543) in real time or under any other time
constraints as required by the application. Enforcing appropriate
coding speed is one function of a controller (550). In some
embodiments, the controller (550) controls other functional units
as described below and is functionally coupled to the other
functional units. The coupling is not depicted for clarity.
Parameters set by the controller (550) can include rate control
related parameters (picture skip, quantizer, lambda value of
rate-distortion optimization techniques, . . . ), picture size,
group of pictures (GOP) layout, maximum motion vector search range,
and so forth. The controller (550) can be configured to have other
suitable functions that pertain to the video encoder (503)
optimized for a certain system design.
In some embodiments, the video encoder (503) is configured to
operate in a coding loop. As an oversimplified description, in an
example, the coding loop can include a source coder (530) (e.g.,
responsible for creating symbols, such as a symbol stream, based on
an input picture to be coded, and a reference picture(s)), and a
(local) decoder (533) embedded in the video encoder (503). The
decoder (533) reconstructs the symbols to create the sample data in
a similar manner as a (remote) decoder also would create (as any
compression between symbols and coded video bitstream is lossless
in the video compression technologies considered in the disclosed
subject matter). The reconstructed sample stream (sample data) is
input to the reference picture memory (534). As the decoding of a
symbol stream leads to bit-exact results independent of decoder
location (local or remote), the content in the reference picture
memory (534) is also bit exact between the local encoder and remote
encoder. In other words, the prediction part of an encoder "sees"
as reference picture samples exactly the same sample values as a
decoder would "see" when using prediction during decoding. This
fundamental principle of reference picture synchronicity (and
resulting drift, if synchronicity cannot be maintained, for example
because of channel errors) is used in some related arts as
well.
The operation of the "local" decoder (533) can be the same as of a
"remote" decoder, such as the video decoder (410), which has
already been described in detail above in conjunction with FIG. 4.
Briefly referring also to FIG. 4, however, as symbols are available
and encoding/decoding of symbols to a coded video sequence by an
entropy coder (545) and the parser (420) can be lossless, the
entropy decoding parts of the video decoder (410), including the
buffer memory (415), and parser (420) may not be fully implemented
in the local decoder (533).
An observation that can be made at this point is that any decoder
technology except the parsing/entropy decoding that is present in a
decoder also necessarily needs to be present, in substantially
identical functional form, in a corresponding encoder. For this
reason, the disclosed subject matter focuses on decoder operation.
The description of encoder technologies can be abbreviated as they
are the inverse of the comprehensively described decoder
technologies. Only in certain areas a more detail description is
required and provided below.
During operation, in some examples, the source coder (530) may
perform motion compensated predictive coding, which codes an input
picture predictively with reference to one or more previously-coded
picture from the video sequence that were designated as "reference
pictures". In this manner, the coding engine (532) codes
differences between pixel blocks of an input picture and pixel
blocks of reference picture(s) that may be selected as prediction
reference(s) to the input picture.
The local video decoder (533) may decode coded video data of
pictures that may be designated as reference pictures, based on
symbols created by the source coder (530). Operations of the coding
engine (532) may advantageously be lossy processes. When the coded
video data may be decoded at a video decoder (not shown in FIG. 5),
the reconstructed video sequence typically may be a replica of the
source video sequence with some errors. The local video decoder
(533) replicates decoding processes that may be performed by the
video decoder on reference pictures and may cause reconstructed
reference pictures to be stored in the reference picture cache
(534). In this manner, the video encoder (503) may store copies of
reconstructed reference pictures locally that have common content
as the reconstructed reference pictures that will be obtained by a
far-end video decoder (absent transmission errors).
The predictor (535) may perform prediction searches for the coding
engine (532). That is, for a new picture to be coded, the predictor
(535) may search the reference picture memory (534) for sample data
(as candidate reference pixel blocks) or certain metadata such as
reference picture motion vectors, block shapes, and so on, that may
serve as an appropriate prediction reference for the new pictures.
The predictor (535) may operate on a sample block-by-pixel block
basis to find appropriate prediction references. In some cases, as
determined by search results obtained by the predictor (535), an
input picture may have prediction references drawn from multiple
reference pictures stored in the reference picture memory
(534).
The controller (550) may manage coding operations of the source
coder (530), including, for example, setting of parameters and
subgroup parameters used for encoding the video data.
Output of all aforementioned functional units may be subjected to
entropy coding in the entropy coder (545). The entropy coder (545)
translates the symbols as generated by the various functional units
into a coded video sequence, by lossless compressing the symbols
according to technologies such as Huffman coding, variable length
coding, arithmetic coding, and so forth.
The transmitter (540) may buffer the coded video sequence(s) as
created by the entropy coder (545) to prepare for transmission via
a communication channel (560), which may be a hardware/software
link to a storage device which would store the encoded video data.
The transmitter (540) may merge coded video data from the video
coder (503) with other data to be transmitted, for example, coded
audio data and/or ancillary data streams (sources not shown).
The controller (550) may manage operation of the video encoder
(503). During coding, the controller (550) may assign to each coded
picture a certain coded picture type, which may affect the coding
techniques that may be applied to the respective picture. For
example, pictures often may be assigned as one of the following
picture types:
An Infra Picture (I picture) may be one that may be coded and
decoded without using any other picture in the sequence as a source
of prediction. Some video codecs allow for different types of intra
pictures, including, for example Independent Decoder Refresh
("IDR") Pictures. A person skilled in the art is aware of those
variants of I pictures and their respective applications and
features.
A predictive picture (P picture) may be one that may be coded and
decoded using intra prediction or inter prediction using at most
one motion vector and reference index to predict the sample values
of each block.
A bi-directionally predictive picture (B Picture) may be one that
may be coded and decoded using intra prediction or inter prediction
using at most two motion vectors and reference indices to predict
the sample values of each block. Similarly, multiple-predictive
pictures can use more than two reference pictures and associated
metadata for the reconstruction of a single block.
Source pictures commonly may be subdivided spatially into a
plurality of sample blocks (for example, blocks of 4.times.4,
8.times.8, 4.times.8, or 16.times.16 samples each) and coded on a
block-by-block basis. Blocks may be coded predictively with
reference to other (already coded) blocks as determined by the
coding assignment applied to the blocks' respective pictures. For
example, blocks of I pictures may be coded non-predictively or they
may be coded predictively with reference to already coded blocks of
the same picture (spatial prediction or intra prediction). Pixel
blocks of P pictures may be coded predictively, via spatial
prediction or via temporal prediction with reference to one
previously coded reference picture. Blocks of B pictures may be
coded predictively, via spatial prediction or via temporal
prediction with reference to one or two previously coded reference
pictures.
The video encoder (503) may perform coding operations according to
a predetermined video coding technology or standard, such as ITU-T
Rec. H.265. In its operation, the video encoder (503) may perform
various compression operations, including predictive coding
operations that exploit temporal and spatial redundancies in the
input video sequence. The coded video data, therefore, may conform
to a syntax specified by the video coding technology or standard
being used.
In an embodiment, the transmitter (540) may transmit additional
data with the encoded video. The source coder (530) may include
such data as part of the coded video sequence. Additional data may
comprise temporal/spatial/SNR enhancement layers, other forms of
redundant data such as redundant pictures and slices, SEI messages,
VUI parameter set fragments, and so on.
A video may be captured as a plurality of source pictures (video
pictures) in a temporal sequence. Intra-picture prediction (often
abbreviated to intra prediction) makes use of spatial correlation
in a given picture, and inter-picture prediction makes uses of the
(temporal or other) correlation between the pictures. In an
example, a specific picture under encoding/decoding, which is
referred to as a current picture, is partitioned into blocks. When
a block in the current picture is similar to a reference block in a
previously coded and still buffered reference picture in the video,
the block in the current picture can be coded by a vector that is
referred to as a motion vector. The motion vector points to the
reference block in the reference picture, and can have a third
dimension identifying the reference picture, in case multiple
reference pictures are in use.
In some embodiments, a bi-prediction technique can be used in the
inter-picture prediction. According to the bi-prediction technique,
two reference pictures, such as a first reference picture and a
second reference picture that are both prior in decoding order to
the current picture in the video (but may be in the past and
future, respectively, in display order) are used. A block in the
current picture can be coded by a first motion vector that points
to a first reference block in the first reference picture, and a
second motion vector that points to a second reference block in the
second reference picture. The block can be predicted by a
combination of the first reference block and the second reference
block.
Further, a merge mode technique can be used in the inter-picture
prediction to improve coding efficiency.
According to some embodiments of the disclosure, predictions, such
as inter-picture predictions and intra-picture predictions are
performed in the unit of blocks. For example, according to the HEVC
standard, a picture in a sequence of video pictures is partitioned
into coding tree units (CTU) for compression, the CTUs in a picture
have the same size, such as 64.times.64 pixels, 32.times.32 pixels,
or 16.times.16 pixels. In general, a CTU includes three coding tree
blocks (CTBs), which are one luma CTB and two chroma CTBs. Each CTU
can be recursively quadtree split into one or multiple coding units
(CUs). For example, a CTU of 64.times.64 pixels can be split into
one CU of 64.times.64 pixels, or 4 CUs of 32.times.32 pixels, or 16
CUs of 16.times.16 pixels. In an example, each CU is analyzed to
determine a prediction type for the CU, such as an inter prediction
type or an intra prediction type. The CU is split into one or more
prediction units (PUs) depending on the temporal and/or spatial
predictability. Generally, each PU includes a luma prediction block
(PB), and two chroma PBs. In an embodiment, a prediction operation
in coding (encoding/decoding) is performed in the unit of a
prediction block. Using a luma prediction block as an example of a
prediction block, the prediction block includes a matrix of values
(e.g., luma values) for pixels, such as 8.times.8 pixels,
16.times.16 pixels, 8.times.16 pixels, 16.times.8 pixels, and the
like.
FIG. 6 shows a diagram of a video encoder (603) according to
another embodiment of the disclosure. The video encoder (603) is
configured to receive a processing block (e.g., a prediction block)
of sample values within a current video picture in a sequence of
video pictures, and encode the processing block into a coded
picture that is part of a coded video sequence. In an example, the
video encoder (603) is used in the place of the video encoder (303)
in the FIG. 3 example.
In an HEVC example, the video encoder (603) receives a matrix of
sample values for a processing block, such as a prediction block of
8.times.8 samples, and the like. The video encoder (603) determines
whether the processing block is best coded using intra mode, inter
mode, or bi-prediction mode using, for example, rate-distortion
optimization. When the processing block is to be coded in intra
mode, the video encoder (603) may use an intra prediction technique
to encode the processing block into the coded picture; and when the
processing block is to be coded in inter mode or bi-prediction
mode, the video encoder (603) may use an inter prediction or
bi-prediction technique, respectively, to encode the processing
block into the coded picture. In certain video coding technologies,
merge mode can be an inter picture prediction submode where the
motion vector is derived from one or more motion vector predictors
without the benefit of a coded motion vector component outside the
predictors. In certain other video coding technologies, a motion
vector component applicable to the subject block may be present. In
an example, the video encoder (603) includes other components, such
as a mode decision module (not shown) to determine the mode of the
processing blocks.
In the FIG. 6 example, the video encoder (603) includes the inter
encoder (630), an intra encoder (622), a residue calculator (623),
a switch (626), a residue encoder (624), a general controller
(621), and an entropy encoder (625) coupled together as shown in
FIG. 6.
The inter encoder (630) is configured to receive the samples of the
current block (e.g., a processing block), compare the block to one
or more reference blocks in reference pictures (e.g., blocks in
previous pictures and later pictures), generate inter prediction
information (e.g., description of redundant information according
to inter encoding technique, motion vectors, merge mode
information), and calculate inter prediction results (e.g.,
predicted block) based on the inter prediction information using
any suitable technique. In some examples, the reference pictures
are decoded reference pictures that are decoded based on the
encoded video information.
The intra encoder (622) is configured to receive the samples of the
current block (e.g., a processing block), in some cases compare the
block to blocks already coded in the same picture, generate
quantized coefficients after transform, and in some cases also
intra prediction information (e.g., an intra prediction direction
information according to one or more intra encoding techniques). In
an example, the intra encoder (622) also calculates intra
prediction results (e.g., predicted block) based on the intra
prediction information and reference blocks in the same
picture.
The general controller (621) is configured to determine general
control data and control other components of the video encoder
(603) based on the general control data. In an example, the general
controller (621) determines the mode of the block, and provides a
control signal to the switch (626) based on the mode. For example,
when the mode is the intra mode, the general controller (621)
controls the switch (626) to select the intra mode result for use
by the residue calculator (623), and controls the entropy encoder
(625) to select the intra prediction information and include the
intra prediction information in the bitstream; and when the mode is
the inter mode, the general controller (621) controls the switch
(626) to select the inter prediction result for use by the residue
calculator (623), and controls the entropy encoder (625) to select
the inter prediction information and include the inter prediction
information in the bitstream.
The residue calculator (623) is configured to calculate a
difference (residue data) between the received block and prediction
results selected from the intra encoder (622) or the inter encoder
(630). The residue encoder (624) is configured to operate based on
the residue data to encode the residue data to generate the
transform coefficients. In an example, the residue encoder (624) is
configured to convert the residue data from a spatial domain to a
frequency domain, and generate the transform coefficients. The
transform coefficients are then subject to quantization processing
to obtain quantized transform coefficients. In various embodiments,
the video encoder (603) also includes a residue decoder (628). The
residue decoder (628) is configured to perform inverse-transform,
and generate the decoded residue data. The decoded residue data can
be suitably used by the intra encoder (622) and the inter encoder
(630). For example, the inter encoder (630) can generate decoded
blocks based on the decoded residue data and inter prediction
information, and the intra encoder (622) can generate decoded
blocks based on the decoded residue data and the intra prediction
information. The decoded blocks are suitably processed to generate
decoded pictures and the decoded pictures can be buffered in a
memory circuit (not shown) and used as reference pictures in some
examples.
The entropy encoder (625) is configured to format the bitstream to
include the encoded block. The entropy encoder (625) is configured
to include various information according to a suitable standard,
such as the HEVC standard. In an example, the entropy encoder (625)
is configured to include the general control data, the selected
prediction information (e.g., intra prediction information or inter
prediction information), the residue information, and other
suitable information in the bitstream. Note that, according to the
disclosed subject matter, when coding a block in the merge submode
of either inter mode or bi-prediction mode, there is no residue
information.
FIG. 7 shows a diagram of a video decoder (710) according to
another embodiment of the disclosure. The video decoder (710) is
configured to receive coded pictures that are part of a coded video
sequence, and decode the coded pictures to generate reconstructed
pictures. In an example, the video decoder (710) is used in the
place of the video decoder (310) in the FIG. 3 example.
In the FIG. 7 example, the video decoder (710) includes an entropy
decoder (771), an inter decoder (780), a residue decoder (773), a
reconstruction module (774), and an intra decoder (772) coupled
together as shown in FIG. 7.
The entropy decoder (771) can be configured to reconstruct, from
the coded picture, certain symbols that represent the syntax
elements of which the coded picture is made up. Such symbols can
include, for example, the mode in which a block is coded (such as,
for example, intra mode, inter mode, bi-predicted mode, the latter
two in merge submode or another submode), prediction information
(such as, for example, intra prediction information or inter
prediction information) that can identify certain sample or
metadata that is used for prediction by the intra decoder (772) or
the inter decoder (780), respectively, residual information in the
form of, for example, quantized transform coefficients, and the
like. In an example, when the prediction mode is inter or
bi-predicted mode, the inter prediction information is provided to
the inter decoder (780); and when the prediction type is the intra
prediction type, the intra prediction information is provided to
the intra decoder (772). The residual information can be subject to
inverse quantization and is provided to the residue decoder
(773).
The inter decoder (780) is configured to receive the inter
prediction information, and generate inter prediction results based
on the inter prediction information.
The intra decoder (772) is configured to receive the intra
prediction information, and generate prediction results based on
the intra prediction information.
The residue decoder (773) is configured to perform inverse
quantization to extract de-quantized transform coefficients, and
process the de-quantized transform coefficients to convert the
residual from the frequency domain to the spatial domain. The
residue decoder (773) may also require certain control information
(to include the Quantizer Parameter (QP)), and that information may
be provided by the entropy decoder (771) (data path not depicted as
this may be low volume control information only).
The reconstruction module (774) is configured to combine, in the
spatial domain, the residual as output by the residue decoder (773)
and the prediction results (as output by the inter or intra
prediction modules as the case may be) to form a reconstructed
block, that may be part of the reconstructed picture, which in turn
may be part of the reconstructed video. It is noted that other
suitable operations, such as a deblocking operation and the like,
can be performed to improve the visual quality.
It is noted that the video encoders (303), (503), and (603), and
the video decoders (310), (410), and (710) can be implemented using
any suitable technique. In an embodiment, the video encoders (303),
(503), and (603), and the video decoders (310), (410), and (710)
can be implemented using one or more integrated circuits. In
another embodiment, the video encoders (303), (503), and (503), and
the video decoders (310), (410), and (710) can be implemented using
one or more processors that execute software instructions.
II. Separately Coding Video Color Components
Video coding technologies typically assume that a to-be-encoded
video sequence has multiple color planes (e.g., one luma component
and two chroma components). By employing certain coding tools, the
color planes can be encoded jointly. For example, luma and chroma
components of a same picture may share a same partitioning tree.
Coded luma and chroma components can be organized into a same CU.
Coding of chroma components may reference pixel values or residual
values of a luma component for prediction (e.g., cross component
linear model (CCLM)). A processing step may use three luma and
chroma components as input (e.g., active color transform (ACT)).
Or, two chroma components can be coded jointly (e.g., joint coding
of chroma residuals (JCCR)).
However, in some applications, either a video is monochrome, or
multiple color planes of a video are required to be encoded
independently. For example, three color components of a video
having a 4:4:4 chroma format may be required to be coded separately
and independently. For example, each color component of the video
is treated as a monochrome video. There is no dependency between
those color components while the video being coded. Coding tools
depending on multiple components (e.g., ACT and JCCR) or operating
on chroma components (e.g., block-based delta (or differential)
pulse code modulation (BDPCM)) are not employed. Coding of the
video is based on monochrome coding tools operating on luma
component.
To support coding of videos with different chroma formats and
videos including one or more monochrome components, in some
embodiments, two syntax elements are defined as shown in Table
1.
TABLE-US-00001 TABLE 1 chroma_format_idc separate_colour_plane_flag
Chroma format 0 0 Monochrome 1 0 4:2:0 2 0 4:2:2 3 0 4:4:4 3 1
4:4:4
The syntax element, chroma_format_idc, provides an index to
multiple chroma formats. The defined chroma formats correspond to
different chroma component sampling structures. Specifically, in
monochrome sampling, there is only one sample array, which is
nominally considered a luma array. In 4:2:0 sampling, each of the
two chroma arrays can have half the height and half the width of
the luma array. In 4:2:2 sampling, each of the two chroma arrays
can have the same height and half the width of the luma array. For
convenience of notation and terminology in this disclosure, the
variables and terms associated with these arrays are referred to as
luma and chroma. The two chroma arrays are referred to as Cb and Cr
regardless of the actual color representation method in use. The
actual color representation method in use can be indicated in
syntax transmitted in a bitstream.
The syntax element, separate_colour_plane_flag, indicates whether
color components of a video sequence are required to be coded
separately. For example, separate_colour_plane_flag equal to 1
specifies that the three color components of the 4:4:4 chroma
format can be coded separately. separate_colour_plane_flag equal to
0 specifies that the color components are not coded separately.
When separate_colour_plane_flag is not present, it is inferred to
be equal to 0.
When separate_colour_plane_flag is equal to 1, the coded picture
consists of three separate components, each of which consists of
coded samples of one color plane (e.g., Y, Cb, or Cr) and uses
monochrome coding syntax. In this case, each color plane is
associated with a specific colour_plane_id value. There is no
dependency in decoding processes between the color planes having
different colour_plane_id values. For example, the decoding process
of a monochrome picture with one value of colour_plane_id does not
use any data from monochrome pictures having different values of
colour_plane_id for inter or intra prediction.
In 4:4:4 sampling, each of the two chroma arrays has the same
height and width as the luma array, and depending on the value of
separate_colour_plane_flag, the following can apply. If
separate_colour_plane_flag is equal to 0, the three color planes
are not separately processed as monochrome sampled pictures.
Otherwise (separate_colour_plane_flag is equal to 1), the three
color planes are separately processed as monochrome sampled
pictures.
In an example, the syntax elements, chroma_format_idc and
separate_colour_plane_flag, are signaled in a sequence parameter
set (SPS) as shown in Table 2. At row 11 of Table 2,
chroma_format_idc is signaled. At row 12, whether chroma_forma_idc
indicates the 4:4:4 chroma format sampling structure is verified.
At row 13, when the chroma_format_idc has a value of 3,
separate_colour_plane_flag is signaled to indicate whether
components of a video sequence referencing the SPS of Table 2 are
coded separately.
When a video is a monochrome video or is required to encode each
color component of the video as if each component is monochrome,
joint color plane coding tools or chroma component based coding
tools are not applicable and can be disabled. However, as shown in
Table 2, several syntax elements controlling those inapplicable
coding tools are signaled independently from whether separate
encoding of color components is enabled (or required). As a result,
some coding tools inapplicable to monochrome videos can still be
enabled when separate encoding of different color planes as
monochrome videos is employed for a current video, causing
undesirable conflicts.
Specifically, at row 86 of Table 2, a syntax element,
sps_joint_cbcr_enabled_flag, is signaled without dependency on the
sperate_colour_plane_flag signaled at row 13. The
sps_joint_cbcr_enabled_flag can indicate whether the joint coding
of chroma residuals (JCCR) tool is enabled for coding a video. As
two chroma components of a CU are jointly coded, the JCCR coding
tool is not a monochrome coding tool. The
sps_joint_cbcr_enabled_flag equal to 0 specifies that the joint
coding of chroma residuals is disabled. The
sps_joint_cbcr_enabled_flag equal to 1 specifies that the joint
coding of chroma residuals is enabled.
At rows 104-105, when BDPCM is enabled and the chroma format is
4:4:4, a syntax element, sps_bdpcm_chroma_enabled_flag, is signaled
without dependency on the sperate_colour_plane_flag signaled at row
13. The sperate_colour_plane_flag can indicate whether the tool of
BDPCM for chroma is enabled for coding a video. The BDPCM for
chroma is a coding tool applied to chroma component, and thus can
be disabled if the video is monochrome, or is required to encode
each color component of the video as if each component is
monochrome.
Regarding the semantics, sps_bdpcm_chroma_enabled_flag equal to 1
specifies that intra_bdpcm_chroma_flag may be present in coding
unit syntax for intra coding units. sps_bdpcm_chroma_enabled_flag
equal to 0 specifies that intra_bdpcm_chromallag is not present in
the coding unit syntax for intra coding units. When not present,
the value of sps_bdpcm_chroma_enabled_flag is inferred to be equal
to 0. Intra_bdpcm_chroma_flag equal to 1 specifies that BDPCM is
applied to current chroma coding blocks, i.e. the transform is
skipped, the intra chroma prediction mode is specified by
intra_bdpcm_chroma_dir_flag. intra_bdpcm_chroma_flag equal to 0
specifies that BDPCM is not applied to the current chroma coding
blocks. When intra_bdpcm_chroma_flag is not present it is inferred
to be equal to 0.
At rows 142 and 144 of Table 2, when the chroma format is 4:4:4, a
syntax element, sps_act_enabled_flag, is signaled without
dependency on the sperate_colour_plane_flag signaled at row 13. The
sps_act_enabled_flag can indicate whether the ACT tool is enabled
for coding a video. For example, a color format (e.g., RGB) in an
original color space can have high correlations among three color
components. By performing a color space conversion, the color
format can be converted from the original color space to a target
color space to reduce redundancy among the three color components.
For example, in HEVC or VCC, the ACT can be performed in spatial
residual domain to convert residual blocks from RGB color space to
YCgCo color space. The residual blocks of three components are used
as input. Thus, ACT is not applicable to a monochrome video or a
video having color components processed separately.
Regarding the semantics, sps_act_enabled_flag specifies that
whether adaptive color transform is enabled. If
sps_act_enabled_flag is equal to 1, adaptive color transform may be
used and the flag cu_act_enabled_flag may be present in the coding
unit syntax. If sps_act_enabled_flag is equal to 0, adaptive color
transform is not used and cu_act_enabled_flag is not present in the
coding unit syntax. When sps_act_enabled_flag is not present, it is
inferred to be equal to 0.
TABLE-US-00002 TABLE 2 Descriptor 1 seq_parameter_set_rbsp( ) { 2
sps_decoding_parameter_set_id u(4) 3 sps_video_parameter_set_id
u(4) 4 sps_max_sub_layers_minusl u(3) 5 sps_reserved_zero_4bits
u(4) 6 sps_ptl_dpb_hrd_params_present_flag u(1) 7 if(
sps_ptl_dpb_hrd_params_present_flag ) 8 profile_tier_level( 1,
sps_max_sub_layers_minus1 ) 9 gdr_enabled_flag u(1) 10
sps_seq_parameter_set_id u(4) 11 ** chroma_format_idc u(2) 12 **
if( chroma_format_idc = = 3 ) 13 ** separate_colour_plane_flag u(1)
14 ref_pic_resampling_enabled_flag u(1) 15 sps_seq_parameter_set_id
ue(v) 16 chroma_format_idc ue(v) 17 pic_width_max_in_luma_samples
ue(v) 18 pic_height_max_in_luma_samples ue(v) 19
sps_log2_ctu_size_minus5 u(2) 20 subpics_present_flag u(1) 21
sps_num_subpics_minus1 u(8) 22 for( i = 0; i <=
sps_num_subpics_minus1; i++ ) { 23 subpic_ctu_top_left_x[ i ] u(v)
24 subpic_ctu_top_left_y[ i ] u(v) 25 subpic_width_minus1[ i ] u(v)
26 subpic_height_minus1[ i ] u(v) 27 subpic_treated_as_pic_flag[ i
] u(1) 28 loop_filter_across_subpic_enabled_flag[ i ] u(1) 29 } 30
} 31 sps_subpic_id_present_flag u(1) 32 if(
sps_subpics_id_present_flag ) { 33
sps_subpic_id_signalling_present_flag u(1) 34 if(
sps_subpics_id_signalling_present_flag ) { 35
sps_subpic_id_len_minus1 ue(v) 36 for( i = 0; i <=
sps_num_subpics_minus1; i++ ) 37 sps_subpic_id[ i ] u(v) 38 } 39 }
40 bit_depth_minus8 ue(v) 41 min_qp_prime_ts_minus4 ue(v) 42
sps_weighted_pred_flag u(1) 43 sps_weighted_bipred_flag u(1) 44
log2_max_pic_order_cnt_lsb_minus4 u(4) 45 sps_poc_msb_flag u(1) 46
if( sps_poc_msb_flag ) 47 poc_msb_len_minus1 ue(v) 48 if(
sps_max_sub_layers_minus1 > 0 ) 49 sps_sub_layer_dpb_params_flag
u(1) 50 if( sps_ptl_dpb_hrd_params_present_flag ) 51
dpb_parameters( 0, sps_max_sub_layers_minus1,
sps_sub_layer_dpb_params_flag ) 52 long_term_ref_pics_flag u(1) 53
inter_layer_ref_pics_present_flag u(1) 54 sps_idr_rpl_present_flag
u(1) 55 rpl1_same_as_rpl0_flag u(1) 56 for( i = 0; i <
!rpl1_samc_as_rpl0_flag ? 2 : 1; i++ ) { 57
num_ref_pic_lists_in_sps[ i ] ue(v) 58 for( j = 0; j <
num_ref_pic_lists_in_sps[ i ]; j++) 59 ref_pic_list_struct( i, j )
60 } 61 if( ChromaArrayType != 0 ) 62 qtbtt_dual_tree_intra_flag
u(1) 63 log2_min_luma_coding_block_size_minus2 ue(v) 64
partition_constraints_override_enabled_flag u(1) 65
sps_log2_diff_min_qt_min_cb_intra_slice_luma ue(v) 66
sps_log2_diff_min_qt_min_cb_inter_slice ue(v) 67
sps_max_mtt_hierarchy_depth_inter_slice ue(v) 68
sps_max_mtt_hierarchy_depth_intra_slice_luma ue(v) 69 if(
sps_max_mtt_hierarchy_depth_intra_slice_luma != 0 ) { 70
sps_log2_diff_max_bt_min_qt_intra_slice_luma ue(v) 71
sps_log2_diff_max_tt_min_qt_intra_slice_luma ue(v) 72 } 73 if(
sps_max_mtt_hierarchy_depth_inter_slice != 0 ) { 74
sps_log2_diff_max_bt_min_qt_inter_slice ue(v) 75
sps_log2_diff_max_tt_min_qt_inter_slice ue(v) 76 } 77 if(
qtbtt_dual_tree_intra_flag ) { 78
sps_log2_diff_min_qt_min_cb_intra_slice_chroma ue(v) 79
sps_max_mtt_hierarchy_depth_intra_slice_chroma ue(v) 80 if(
sps_max_mtt_hierarchy_depth_intra_slice_chroma != 0 ) { 81
sps_log2_diff_max_bt_min_qt_intra_slice_chroma ue(v) 82
sps_log2_diff_max_tt_min_qt_intra_slice_chroma ue(v) 83 } 84 } 85
sps_max_luma_transform_size_64_flag u(1) 86 **
sps_joint_cbcr_enabled_flag u(1) 87 if( ChromaArrayType != 0 ) { 88
same_qp_table_for_chroma u(1) 89 numQpTables =
same_qp_table_for_chroma ? 1 : ( sps_joint_cbcr_enabled_flag ? 3 :
2 ) 90 for( i = 0; i < numQpTables; i++ ) { 91
qp_table_start_minus26[ i ] se(v) 92 num_points_in_qp_table_minus1[
i ] ue(v) 93 for( j = 0; j <= num_points_in_qp_table_minus1[ i
]; j++ ) { 94 delta_qp_in_val_minus1[ i ][ j ] ue(v) 95
delta_qp_diff_val[ i ][ j ] ue(v) 96 } 97 } 98 } 99
sps_sao_enabled_flag u(1) 100 sps_alf_enabled_flag u(1) 101
sps_transform_skip_enabled_flag u(1) 102 if(
sps_transform_skip_enabled_flag ) 103 sps_bdpcm_enabled_flag u(1)
104 ** if( sps_bdpcm_enabled_flag && chroma_format_idc = =
3 ) 105 ** sps_bdpcm_chroma_enabled_flag u(1) 106
sps_ref_wraparound_enabled_flag u(1) 107 if(
sps_ref_wraparound_enabled_flag ) 108
sps_ref_wraparound_offset_minus1 ue(v) 109
sps_temporal_mvp_enabled_flag u(1) 110 if(
sps_temporal_mvp_enabled_flag ) 111 sps_sbtmvp_enabled_flag u(1)
112 sps_amvr_enabled_flag u(1) 113 sps_bdof_enabled_flag u(1) 114
if( sps_bdof_enabled_fiag ) 115 sps_bdof_pic_present_flag u(1) 116
sps_smvd_enabled_flag u(1) 117 sps_dmvr_enabled_flag u(1) 118 if(
sps_dmvr_enabled_flag) 119 sps_dmvr_pic_present_flag u(1) 120
sps_mmvd_enabled_flag u(1) 121 sps_isp_enabled_flag u(1) 122
sps_mrl_enabled_flag u(1) 123 sps_mip_enabled_flag u(1) 124 if(
ChromaArrayType != 0 ) 125 sps_cclm_enabled_flag u(1) 126 if(
sps_cclm_enabled_flag && chroma_format_idc = = 1 ) [Ed.
(JC): should sps_cclm_colocated_chroma_flag also be signalled for
422 case since it's used in the decoding process, to be confirmed]
127 sps_cclm_colocated_chroma_flag u(1) 128 sps_mts_enabled_flag
u(1) 129 if( sps_mts_enabled_flag ) { 130
sps_explicit_mts_intra_enabled_flag u(1) 131
sps_explicit_mts_inter_enabled_flag u(1) 132 } 133
sps_sbt_enabled_flag u(1) 134 sps_affine_enabled_flag u(1) 135 if(
sps_affine_enabled_flag ) { 136 sps_affine_type_flag u(1) 137
sps_affine_amvr_enabled_flag u(1) 138 sps_affine_prof_enabled_flag
u(1) 139 if( sps_affine_prof_enabled_flag ) 140
sps_prof_pic_present_flag u(1) 141 } 142 ** if( chroma_format_idc =
= 3 ) { 143 sps_palette_enabled_flag u(1) 144 **
sps_act_enabled_flag u(1) 145 } 146 sps_bcw_enabled_flag u(1) 147
sps_ibc_enabled_flag u(1) 148 sps_ciip_enabled_flag u(1) 149 if(
sps_mmvd_enabled_flag ) 150 sps_fpel_mmvd_enabled_flag u(1) 151
sps_triangle_enabled_flag u(1) 152 sps_lmcs_enabled_flag u(1) 153
sps_lfnst_enabled_flag u(1) 154 sps_ladf_enabled_flag u(1) 155 if(
sps_ladf_enabled_flag ) { 156 sps_num_ladf_intervals_minus2 u(2)
157 sps_ladf_lowest_intenal_qp_offset se(v) 158 for( i = 0; i <
sps_num_ladf_intervals_minus2 + 1; i++ ) { 159 sps_ladf_qp_offset[
i ] se(v) 160 sps_ladf_delta_threshold_minus1[ i ] ue(v) 161 } 162
} 163 sps_scaling_list_enabled_flag u(1) 164
sps_loop_filter_across_virtual_boundaries_disabled_present_flag
u(1) 165 if(
sps_loop_filter_across_virtual_boundaries_disabled_present_flag ) {
166 sps_num_ver_virtual_boundaries u(2) 167 for( i = 0; i <
sps_num_ver_virtual_boundaries; i++ ) 168
sps_virtual_boundaries_pos_x[ i ] u(13) 169
sps_num_hor_virtual_boundaries u(2) 170 for( i = 0; i <
sps_num_hor_virtual_boundaries; i++ ) 171
sps_virtual_boundaries_pos_y[ i ] u(13) 172 } 173 if(
sps_ptl_dpb_hrd_params_present_flag ) { 174
sps_general_hrd_params_present_flag u(1) 175 if(
sps_general_hrd_params_present_flag ) { 176 general_hrd_parameters(
) 177 if( sps_max_sub_layers_minus1 > 0 ) 178
sps_sub_layer_cpb_params_present_flag u(1) 179 firstSubLayer =
sps_sub_layer_cpb_params_present_flag ? 0 :
sps_max_sub_layers_minus1 180 ols_hrd_parameters( firstSubLayer,
sps_max_sub_layers_minus1 ) 181 } 182 } 183
vui_parameters_present_flag u(1) 184 if(
vui_parameters_present_flag ) 185 vui_parameters( ) 186
sps_extension_flag u(1) 187 if( sps_extension_flag ) 188 while(
more_rbsp_data( ) ) 189 sps_extension_data_flag u(1) 190
rbsp_trailing_bits( ) 191 }
III. Disabling Coding Tools Inapplicable to Monochrome Video or
Video with Separately Coded Components
In some embodiments, to support the coding of monochrome video and
the separate coding of three color components of, for example, a
4:4:4 chroma format video, a variable indicating a chroma array
type is defined. The variable is denoted by ChromaArrayType. The
variable ChromaArrayType can be used to disable the coding tools
that are not applicable when the video is monochrome and when the
color components of the video are required to be encoded separately
and independently. Depending on the value of
separate_colour_plane_flag, the value of the variable
ChromaArrayType can be assigned as follows: If
separate_colour_plane_flag is equal to 0, ChromaArrayType is set
equal to chroma_format_idc (e.g., 0, 1, 2, or 3). Otherwise
(separate_colour_plane_flag is equal to 1), ChromaArrayType is set
equal to 0. When ChromaArrayType is 0, the coding tools enabled by
sps_joint_cbcr_enabled_flag, sps_act_enabled_flag,
sps_bdpcm_chroma_enabled_flag, or the like can be disabled.
Table 3 shows a modified version of the SPS syntax shown in Table
2. At rows 84-85 of Table 3, sps_joint_cbcr_enabled_flag is
signaled when ChromaArrayType has a non-zero value. When
ChromaArrayType equals zero, which indicates a current video
referring the SPS of Table 2 is monochrome, or includes separately
encoded components, sps_joint_cbcr_enabled_flag is not signaled,
and can be inferred to be equal to zero. Accordingly, the joint
coding of chroma residuals can be disabled. Compared with the Table
2 examples, semantics of sps_joint_cbcr_enabled_flag can be
modified as follows: sps_joint_cbcr_enabled_flag equal to 0
specifies that the joint coding of chroma residuals is disabled.
sps_joint_cbcr_enabled_flag equal to 1 specifies that the joint
coding of chroma residuals is enabled. When
sps_joint_cbcr_enabled_flag is not present, it is inferred to be be
equal to 0.
At rows 102-103 of Table 3, sps_bdpcm_chroma_enabled_flag is
signaled when BDPCM is enabled and ChromaArrayType has a non-zero
value. When ChromaArrayType equals zero,
sps_bdpcm_chroma_enabled_flag is not signaled, and can be inferred
to be equal to zero. Accordingly, the BDPCM for chroma can be
disabled. Semantics of sps_bdpcm_chroma_enabled_flag can be the
same as in the Table 2 example.
At rows 140, 142, and 143 of Table 3, sps_act_enabled_flag is
signaled when the video has a 4:4:4 chroma format and
ChromaArrayType has a non-zero value. When ChromaArrayType equals
zero, sps_act_enabled_flag is not signaled, and can be inferred to
be equal to zero. Accordingly, the ACT can be disabled. Semantics
of sps_act_enabled_flag can be the same as in the Table 2
example.
TABLE-US-00003 TABLE 3 Descriptor 1 seq_parameter_set_rbsp( ) { 2
sps_decoding_parameter_set_id u(4) 3 sps_video_parameter_set_id
u(4) 4 sps_max_sub_layers_minus1 u(3) 5 sps_reserved_zero_4bits
u(4) 6 sps_ptl_dpb_hrd_params_present_flag u(1) 7 if(
sps_ptl_dpb_hrd_params_present_flag ) 8 profile_tier_level( l,
sps_max_sub_layers_minus1 ) 9 gdr_enabled_flag u(1) 10
sps_seq_parameter_set_id u(4) 11 ** chroma_format_idc u(2) 12 **
if( chroma_format_idc = = 3 ) 13 ** separate_colour_plane_flag u(1)
14 ref_pic_resampling_enabled_flag u(1) 15
pic_width_max_in_luma_samples ue(v) 16
pic_height_max_in_luma_samples ue(v) 17 sps_log2_ctu_size_minus5
u(2) 18 subpics_present_flag u(1) 19 sps_num_subpics_minus1 u(8) 20
for( i = 0; i <= sps_num_subpics_minus1; i++ ) { 21
subpic_ctu_top_left_x[ i ] u(v) 22 subpic_ctu_top_left_y[ i ] u(v)
23 subpic_width_minus1[ i ] u(v) 24 subpic_height_minus1[ i ] u(v)
25 subpic_treated_as_pic_flag[ i ] u(1) 26
loop_filter_across_subpic_enabled_flag[ i ] u(1) 27 } 28 } 29
sps_subpic_id_present_flag u(1) 30 if( sps_subpics_id_present_flag
) { 31 sps_subpic_id_signalling_present_flag u(1) 32 if( sps
subpics id signalling present flag ) { 33 sps_subpic_id_len_minus1
ue(v) 34 for( i = 0; i <= sps_num_subpics_minus1; i++ ) 35
sps_subpic_id[ i ] u(v) 36 } 37 } 38 bit_depth_minus8 ue(v) 39
min_qp_prime_ts_nimus4 ue(v) 40 sps_weighted_pred_flag u(1) 41
sps_weighted_bipred_flag u(1) 42 log2_max_pic_order_cnt_lsb_minus4
u(4) 43 sps_poc_msb_flag u(1) 44 if( sps_poc_msb_flag ) 45
poc_msb_len_minus1 ue(v) 46 if( sps_max_sub_layers_minus1 > 0 )
47 sps_sub_layer_dpb_params_flag u(1) 48 if(
sps_ptl_dpb_hrd_params_present_flag ) 49 dpb_parameters( 0,
sps_max_sub_layers_minus1, sps_sub_layer_dpb_params_flag ) 50
long_term_ref_pics_flag u(1) 51 inter_layer_ref_pics_present_flag
u(1) 52 sps_idr_rpl_present_flag u(1) 53 rpl1_same_as_rpl0_flag
u(1) 54 for( i = 0; i < !rpl1_same_as_rpl0_flag ? 2 : 1; i++ ) {
55 num_ref_pic_lists_in_sps[ i ] ue(v) 56 for( j = 0; j <
num_ref_pic_lists_in_sps[ i ]; j++) 57 ref_pic_list_struct( i, j )
58 } 59 if( ChromaArrayType != 0 ) 60 qtbtt_dual_tree_intra_flag
u(1) 61 log2_min_luma_coding_block_size_minus2 ue(v) 62
partition_constraints_override_enabled_flag u(1) 63
sps_log2_diff_min_qt_min_cb_intra_slice_luma ue(v) 64
sps_log2_diff_min_qt_min_cb_inter_slice ue(v) 65
sps_max_mtt_hierarchy_depth_inter_slice ue(v) 66
sps_max_mtt_hierarchy_depth_intra_slice_luma ue(v) 67 if(
sps_max_mtt_hierarchy_depth_intra_slice_luma != 0 ) { 68
sps_log2_diff_max_bt_min_qt_intra_slice_luma ue(v) 69
sps_log2_diff_max_tt_min_qt_intra_slice_luma ue(v) 70 } 71 if(
sps_max_mtt_hierarchy_depth_inter_slice != 0 ) { 72
sps_log2_diff_max_bt_min_qt_inter_slice ue(v) 73
sps_log2_diff_max_tt_min_qt_inter_slice ue(v) 74 } 75 if(
qtbtt_dual_tree_intra_flag ) { 76
sps_log2_diff_min_qt_min_cb_intra_slice_chroma ue(v) 77
sps_max_mtt_hierarchy_depth_intra_slice_chroma ue(v) 78 if(
sps_max_mtt_hierarchy_depth_intra_slice_chroma != 0 ) { 79
sps_log2_diff_max_bt_min_qt_intra_slice_chroma ue(v) 80
sps_log2_diff_max_tt_min_qt_intra_slice_chroma ue(v) 81 } 82 } 83
sps_max_luma_transform_size_64_flag u(1) 84 ** if( ChromaArrayType
!= 0 ) { u(1) 85 ** sps_joint_cbcr_enabled_flag 86
same_qp_table_for_chroma u(1) 87 numQpTables =
same_qp_table_for_chroma ? 1 : ( sps_joint_cbcr_enabled_flag ? 3 :
2 ) 88 for( i = 0; i < numQpTables; i++ ) { 89
qp_table_start_minus26[ i ] se(v) 90 num_points_in_qp_table_minus1[
i ] ue(v) 91 for( j = 0; j <= num_points_in_qp_table_minus1[ i
]; j++ ) { 92 delta_qp_in_val_minus1[ i ][ j ] ue(v) 93
delta_qp_diff_val[ i ][ j ] ue(v) 94 } 95 } 96 } 97
sps_sao_enabled_flag u(1) 98 sps_alf_enabled_flag u(1) 99
sps_transform_skip_enabled_flag u(1) 100 if(
sps_transform_skip_enabled flag ) 101 sps_bdpcm_enabled_flag u(1)
102 ** if( sps_bdpcm_enabled_flag && ChromaArrayType!=0)
103 ** sps_bdpcm_chroma_enabled_flag u(1) 104
sps_ref_wraparound_enabled_flag u(1) 105 if(
sps_ref_wraparound_enabled_flag ) 106
sps_ref_wraparound_offset_minus1 ue(v) 107
sps_temporal_mvp_enabled_flag u(1) 108 if(
sps_temporal_mvp_enabled_flag ) 109 sps_sbtmvp_enabled_flag u(1)
110 sps_amvr_enabled_flag u(1) 111 sps_bdof_enabled_flag u(1) 112
if( sps_bdof_enabled_flag ) 113 sps_bdof_pic_present_flag u(1) 114
sps_smvd_enabled_flag u(1) 115 sps_dmvr_enabled_flag u(1) 116 if(
sps_dmvr_enabled_flag) 117 sps_dmvr_pic_present_flag u(1) 118
sps_mmvd_enabled_flag u(1) 119 sps_isp_enabled_flag u(1) 120
sps_mrl_enabled flag u(1) 121 sps_mip_enabled_flag u(1) 122 if(
ChromaArrayType != 0 ) 123 sps_cclm_enabled_flag u(1) 124 if(
sps_cclm_enabled_flag && chroma_formal_idc = = 1 ) [Ed.
(JC): should sps_cclm_colocated_chroma_flag also be signalled for
422 case since it's used in the decoding process, to be confirmed]
125 sps_cclm_colocated_chroma_flag u(1) 126 sps_mts_enabled_flag
u(1) 127 if( sps_mts_enabled_flag ) { 128
sps_explicit_mts_intra_enabled_flag u(1) 129
sps_explicit_mts_inter_enabled_flag u(1) 130 } 131
sps_sbt_enabled_flag u(1) 132 sps_affine_enabled_flag u(1) 133 if(
sps_affine_enabled_flag ) { 134 sps_affine_type_flag u(1) 135
sps_afline_amvr_enabled_flag u(1) 136 sps_affine_prof_enabled_flag
u(1) 137 if( sps_affine_prof_enabled_flag ) 138
sps_prof_pic_present_flag u(1) 139 } 140 ** if( chroma_format_idc =
= 3 ) { 141 sps_palette_enabled_flag u(1) 142 ** if(
ChromaArrayType != 0 ) 143 ** sps_act_enabled_flag u(1) 144 } 145
sps_bcw_enabled_flag u(1) 146 sps_ibc_enabled_flag u(1) 147
sps_ciip_enabled_flag u(1) 148 if( sps_mmvd_enabled_flag ) 149
sps_fpel_mmvd_enabled_flag u(1) 150 sps_triangle_enabled_flag u(1)
151 sps_lmcs_enabled_flag u(1) 152 sps_lfnst_enabled_flag u(1) 153
sps_ladf_enabled_flag u(1) 154 if( sps_ladf_enabled_flag ) { 155
sps_num_ladf_intervals_minus2 u(2) 156
sps_ladf_lowest_interval_qp_offset se(v) 157 for( i = 0; i <
sps_num_ladf_intervals_minus2 + 1; i++ ) { 158 sps_ladf_qp_offset[
i ] se(v) 159 sps_ladf_delta_threshold_minus1[ i ] ue(v) 160 } 161
} 162 sps_scaling_list_enabled_flag u(1) 163
sps_loop_filter_across_virtual_boundaries_disabled_present_flag
u(1) 164 if(
sps_loop_filter_across_virtual_boundaries_disabled_present_flag ) {
165 sps_num_ver_virtual_boundaries u(2) 166 for( i = 0; i <
sps_num_ver_virtual_boundaries; i++ ) 167
sps_virtual_boundaries_pos_x[ i ] u(13) 168
sps_num_hor_virtual_boundaries u(2) 169 for( i = 0; i <
sps_num_hor_virtual_boundaries; i++ ) 170
sps_virtual_boundaries_pos_y[ i ] u(13) 171 } 172 if(
sps_ptl_dpb_hrd_params_present_flag ) { 173
sps_general_hrd_params_present_flag u(1) 174 if(
sps_general_hrd_params_present_flag ) { 175 general_hrd_parameters(
) 176 if( sps_max_sub_layers_minus1 > 0 ) 177
sps_sub_layer_cpb_params_present_flag u(1) 178 firstSubLayer =
sps_sub_layer_cpb_params_present_flag ? 0 :
sps_max_sub_layers_minus1 179 ols_hrd_parameters( firstSubLayer,
sps_max_sub_layers_minus1 ) 180 } 181 } 182
vui_parameters_present_flag u(1) 183 if(
vui_parameters_present_flag ) 184 vui_parameters( ) 185
sps_extension_flag u(1) 186 if( sps_extension_flag ) 187 while(
more_rbsp_data( ) ) 188 sps_extension_data_flag u(1) 189
rbsp_trailing_bits( ) 190 }
In some embodiments, alternate implementations are employed for
disabling coding tools inapplicable to a monochrome video or a
video including separately encoded components.
In an embodiment, the following syntax of sps_act_enabled_flag in
Table 4 (which is copied from Table 3) can be expressed with
alternate syntax shown in Table 5 to set the value of
sps_act_enabled_flag to 0 when chroma_format_idc equals 3 and
ChromaArrayType is zero. Since chroma_format_idc==3 and
separate_colour_plan_flag==0 implies ChromaArrayType not 0, the
syntax in Table 4 and Table 5 can have the same effect. It is noted
that the signaling of sps_act_enabled_flag is independent from the
signaling of sps_palette_enabled_flag at row 141.
TABLE-US-00004 TABLE 4 140 ** if( chroma_format_idc = = 3 ) { 141
sps_palette_enabled_flag u(1) 142 ** iff ChromaArrayType != 0 ) 143
** sps_act_enabled_flag u(1) 144 }
TABLE-US-00005 TABLE 5 140 ** if( chroma_format_idc = = 3 ) { 141
sps_palette_enabled_flag u(1) 142 **
if(separate_colour_plane_flag== 0) 143 ** sps_act_enabled_flag u(1)
144 }
In an embodiment, the following syntax of
sps_bdpcm_chroma_enabled_flag in Table 6 (which is copied from
Table 3) can be expressed with alternate syntax as shown in Table 7
to set the value of sps_bdpcm_chroma_enabled_flag to 0 when
ChromaArrayType is zero. In Table 7, the value of
sps_bdpcm_chroma_enabled_flag is inferred to be 0 when
ChromaArrayType is zero or a sps_transpquant_bypass_flag to support
BDPCM for lossless equals 0. When sps_tranquant_bypass_flag equals
1, sps_transquant_bypass_flag indicates that transformation and
quantization pass shall be activated at the CU level. Otherwise, if
sps_tranquant_bypass_flag equals 0, transformation and quantization
bypass shall not be activated. The sps_tranquant_bypass_flag can be
signaled at the SPS or be inferred to be 1 for lossless coding as
indicated by other SPS level lossless coding indication flag.
TABLE-US-00006 TABLE 6 102 ** if( sps_bdpcm_enabled_flag &&
ChromaArrayType!=0) 103 ** sps_bdpcm_chroma_enabled_flag u(1)
TABLE-US-00007 TABLE 7 102 ** if( sps_bdpcm_enabled_flag &&
cu_transquant_bypass_flag &&ChromaArrayType!=0) 103 **
sps_bdpcm_chroma_enabled_flag u(1)
In an embodiment, the syntax in Table 7 is used. However, different
from the above embodiment, the semantics of the syntax element
sps_tranquant_bypass_flag is defined as follows. When
sps_tranquant_bypass_flag equals 1, sps_transquant_bypass_flag
indicates that transformation and quantization pass may (instead of
shall) be activated at the CU level. Otherwise, if
sps_tranquant_bypass_flag equals 0, transformation and quantization
bypass shall not be activated. The sps_tranquant_bypass_flag can be
signaled at the SPS or be inferred to be 1 for lossless coding as
indicated by other SPS level lossless coding indication flag.
FIG. 8 shows an example process (800) of receiving flags of cross
component coding tools or chroma component based coding tools in a
bitstream of a coded video. The process (800) can be performed at a
decoder. The process (800) can start from (S801) and proceed to
(S810).
At S(810), a syntax element can be received in the bitstream that
indicate whether pictures of a sequence each are monochrome or have
separately encoded components. For example, the syntax element can
be the chroma_format_idc, or the separate_color_plane_flag. The
chroma_format_idc being 0 can indicate the pictures are monochrome.
The separate_colorplane_flag being 1 can indicate the pictures each
having separately coded components. In both the cases, the
ChromaArrayType can have a value of 0.
As an example, the sequence of pictures refer the SPS in Table 3.
The chroma_format_idc signaled in row 11 in Table 3 is received.
When the chroma_format_idc has a value of 0, it can be determined
the pictures are monochrome. When the chroma_format_idc equals
zero, the separate_color_plane_flag may not be signaled at row 13,
and can be inferred to be equal to zero in one example.
Accordingly, the ChromaArrayType can be set equal to
chroma_format_idc that is zero for the current case.
When the chroma_format_idc has a value of 3 indicating a 4:4:4
chroma format of the pictures of the sequence, the
separate_colour_plane_flag can be received at row 13. If the
separate_colour_plane_flag has a value of 1, which indicates the
pictures are required to separately coding the components, it can
be determined the pictures have separately encoded components. The
ChromaArrayType can be set equal to zero.
In other cases, when the chroma_format_idc received in row 11 has a
value of 1 or 2, or when the chroma_format_idc received in row 11
has a value of 3 but the separate_colour_plane_flag has a value of
0, it can be determined the pictures each are not monochrome and
include components that are not coded separately. Joint components
coding tools or chroma based coding tools can be applied to the
pictures. For the chroma_format_idc received in row 11 of Table 3
having a value of 1 or 2 (the pictures are not monochrome), the
separate_colour_plane_flag can be inferred as zero. Accordingly,
the ChromeArrayType can take the value of chroma_format_idc that is
1 or 2 (not zero). For the scenario that the chroma_format_idc
received has a value of 3 but the separate_colour_plane_flag has a
value of 0, the ChromeArrayType can still take the value of
chroma_format_idc that is 3 (not zero).
When the pictures are determined to be monochrome or include
separately encoded components, or the ChromaArrayType is determined
to be equal to zero, the steps of (S820) to (S840) can be
performed. The syntax elements for control of the joint-components
coding tools or chroma-based coding tool can be inferred to be
equal to zero to disable those coding tools. Specifically,
sps_joint_cbcr_enabled_flag, sps_bdpcm_chroma_enabled_flag, and
sps_act_enabled_flag are each inferred to be equal to zero.
When the pictures are determined to not be monochrome and include
components that are not separately encoded, or the chromeArrayType
is determined to be not equal zero, the steps of (S850) to (S870)
can be performed. The syntax elements for control of the
joint-components coding tools or chroma-based coding tool can be
received from the bitstream. Specifically,
sps_joint_cbcr_enabled_flag, sps_bdpcm_chroma_enabled_flag, and
sps_act_enabled_flag can be received successively.
After either (S840) or (S870), the process (800) can proceed to
(S899) and terminate at (S899).
FIG. 9 shows a process (900) of disabling coding tools inapplicable
to a monochrome video or a video including separately encoded
components according to an embodiment of the disclosure. The
process (900) can be performed at a decoder such as decoder (710).
The process (900) can start from (S901) and proceed to (S910).
At (S910), a syntax element can be received in a bitstream that
indicate whether a sequence of pictures each are monochrome or have
separately encoded components. For example, the syntax element can
be the chroma_format_idc, or the separate_color_plane_flag in the
Table 3 example. The chroma_format_idc being 0 can indicate the
pictures are monochrome. The separate_color_plane_flag being 1 can
indicate the pictures each having separately coded components. In
both the cases (chroma_format_idc being 0 or
separate_color_plane_flag being 1), the variable ChromaArrayType
can have a value of 0.
When it is determined the sequence of pictures each are monochrome
or have separately encoded components, the steps (S920) and (S930)
can be performed. At (S920), coding tools that use multiple
components of the pictures as input can be disabled, for example,
by inferring a value of a syntax element controlling each
corresponding coding tool. Examples of such coding tools can
include ACT, joint coding of chroma residuals, or the like.
At (S930), coding tools that depend on a chroma component of the
pictures can be disabled, for example, by inferring a value of a
syntax element controlling each corresponding coding tool. Examples
of such coding tools can include BDPCM for chroma. The process
(900) can then proceed to (S999) and terminate at (S999).
When it is determined at (S910) that the sequence of pictures each
are not monochrome or do not have separately encoded components,
the step (S940) can be performed. At (S940), syntax elements for
enabling the joint component coding tools or chroma component based
coding tools can be received from the bit stream. Whether the
syntax elements for enabling those coding tools are signaled in the
bitstream may depending on other conditions or other syntax
elements transmitted in the bitstream. The process (900) can then
proceed to (S999) and terminate at (S999).
IV. Computer System
The techniques described above, can be implemented as computer
software using computer-readable instructions and physically stored
in one or more computer-readable media. For example, FIG. 10 shows
a computer system (1000) suitable for implementing certain
embodiments of the disclosed subject matter.
The computer software can be coded using any suitable machine code
or computer language, that may be subject to assembly, compilation,
linking, or like mechanisms to create code comprising instructions
that can be executed directly, or through interpretation,
micro-code execution, and the like, by one or more computer central
processing units (CPUs), Graphics Processing Units (GPUs), and the
like.
The instructions can be executed on various types of computers or
components thereof, including, for example, personal computers,
tablet computers, servers, smartphones, gaming devices, internet of
things devices, and the like.
The components shown in FIG. 10 for computer system (1000) are
exemplary in nature and are not intended to suggest any limitation
as to the scope of use or functionality of the computer software
implementing embodiments of the present disclosure. Neither should
the configuration of components be interpreted as having any
dependency or requirement relating to any one or combination of
components illustrated in the exemplary embodiment of a computer
system (1000).
Computer system (1000) may include certain human interface input
devices. Such a human interface input device may be responsive to
input by one or more human users through, for example, tactile
input (such as: keystrokes, swipes, data glove movements), audio
input (such as: voice, clapping), visual input (such as: gestures),
olfactory input (not depicted). The human interface devices can
also be used to capture certain media not necessarily directly
related to conscious input by a human, such as audio (such as:
speech, music, ambient sound), images (such as: scanned images,
photographic images obtain from a still image camera), video (such
as two-dimensional video, three-dimensional video including
stereoscopic video).
Input human interface devices may include one or more of (only one
of each depicted): keyboard (1001), mouse (1002), trackpad (1003),
touch screen (1010), data-glove (not shown), joystick (1005),
microphone (1006), scanner (1007), camera (1008).
Computer system (1000) may also include certain human interface
output devices. Such human interface output devices may be
stimulating the senses of one or more human users through, for
example, tactile output, sound, light, and smell/taste. Such human
interface output devices may include tactile output devices (for
example tactile feedback by the touch-screen (1010), data-glove
(not shown), or joystick (1005), but there can also be tactile
feedback devices that do not serve as input devices), audio output
devices (such as: speakers (1009), headphones (not depicted)),
visual output devices (such as screens (1010) to include CRT
screens, LCD screens, plasma screens, OLED screens, each with or
without touch-screen input capability, each with or without tactile
feedback capability--some of which may be capable to output two
dimensional visual output or more than three dimensional output
through means such as stereographic output; virtual-reality glasses
(not depicted), holographic displays and smoke tanks (not
depicted)), and printers (not depicted).
Computer system (1000) can also include human accessible storage
devices and their associated media such as optical media including
CD/DVD ROM/RW (1020) with CD/DVD or the like media (1021),
thumb-drive (1022), removable hard drive or solid state drive
(1023), legacy magnetic media such as tape and floppy disc (not
depicted), specialized ROM/ASIC/PLD based devices such as security
dongles (not depicted), and the like.
Those skilled in the art should also understand that term "computer
readable media" as used in connection with the presently disclosed
subject matter does not encompass transmission media, carrier
waves, or other transitory signals.
Computer system (1000) can also include an interface (1054) to one
or more communication networks (1055). Networks can for example be
wireless, wireline, optical. Networks can further be local,
wide-area, metropolitan, vehicular and industrial, real-time,
delay-tolerant, and so on. Examples of networks include local area
networks such as Ethernet, wireless LANs, cellular networks to
include GSM, 3G, 4G, 5G, LTE and the like, TV wireline or wireless
wide area digital networks to include cable TV, satellite TV, and
terrestrial broadcast TV, vehicular and industrial to include
CANBus, and so forth. Certain networks commonly require external
network interface adapters that attached to certain general purpose
data ports or peripheral buses (1049) (such as, for example USB
ports of the computer system (1000)); others are commonly
integrated into the core of the computer system (1000) by
attachment to a system bus as described below (for example Ethernet
interface into a PC computer system or cellular network interface
into a smartphone computer system). Using any of these networks,
computer system (1000) can communicate with other entities. Such
communication can be uni-directional, receive only (for example,
broadcast TV), uni-directional send-only (for example CANbus to
certain CANbus devices), or bi-directional, for example to other
computer systems using local or wide area digital networks. Certain
protocols and protocol stacks can be used on each of those networks
and network interfaces as described above.
Aforementioned human interface devices, human-accessible storage
devices, and network interfaces can be attached to a core (1040) of
the computer system (1000).
The core (1040) can include one or more Central Processing Units
(CPU) (1041), Graphics Processing Units (GPU) (1042), specialized
programmable processing units in the form of Field Programmable
Gate Areas (FPGA) (1043), hardware accelerators for certain tasks
(1044), graphics adapters (1050), and so forth. These devices,
along with Read-only memory (ROM) (1045), Random-access memory
(1046), internal mass storage such as internal non-user accessible
hard drives, SSDs, and the like (1047), may be connected through a
system bus (1048). In some computer systems, the system bus (1048)
can be accessible in the form of one or more physical plugs to
enable extensions by additional CPUs, GPU, and the like. The
peripheral devices can be attached either directly to the core's
system bus (1048), or through a peripheral bus (1049). In an
example, the screen (.about..about..times.10) can be connected to
the graphics adapter (.about..about..times.50). Architectures for a
peripheral bus include PCI, USB, and the like.
CPUs (1041), GPUs (1042), FPGAs (1043), and accelerators (1044) can
execute certain instructions that, in combination, can make up the
aforementioned computer code. That computer code can be stored in
ROM (1045) or RAM (1046). Transitional data can also be stored in
RAM (1046), whereas permanent data can be stored for example, in
the internal mass storage (1047). Fast storage and retrieve to any
of the memory devices can be enabled through the use of cache
memory, that can be closely associated with one or more CPU (1041),
GPU (1042), mass storage (1047), ROM (1045), RAM (1046), and the
like.
The computer readable media can have computer code thereon for
performing various computer-implemented operations. The media and
computer code can be those specially designed and constructed for
the purposes of the present disclosure, or they can be of the kind
well known and available to those having skill in the computer
software arts.
As an example and not by way of limitation, the computer system
having architecture (1000), and specifically the core (1040) can
provide functionality as a result of processor(s) (including CPUs,
GPUs, FPGA, accelerators, and the like) executing software embodied
in one or more tangible, computer-readable media. Such
computer-readable media can be media associated with
user-accessible mass storage as introduced above, as well as
certain storage of the core (1040) that are of non-transitory
nature, such as core-internal mass storage (1047) or ROM (1045).
The software implementing various embodiments of the present
disclosure can be stored in such devices and executed by core
(1040). A computer-readable medium can include one or more memory
devices or chips, according to particular needs. The software can
cause the core (1040) and specifically the processors therein
(including CPU, GPU, FPGA, and the like) to execute particular
processes or particular parts of particular processes described
herein, including defining data structures stored in RAM (1046) and
modifying such data structures according to the processes defined
by the software. In addition or as an alternative, the computer
system can provide functionality as a result of logic hardwired or
otherwise embodied in a circuit (for example: accelerator (1044)),
which can operate in place of or together with software to execute
particular processes or particular parts of particular processes
described herein. Reference to software can encompass logic, and
vice versa, where appropriate. Reference to a computer-readable
media can encompass a circuit (such as an integrated circuit (IC))
storing software for execution, a circuit embodying logic for
execution, or both, where appropriate. The present disclosure
encompasses any suitable combination of hardware and software.
APPENDIX A: ACRONYMS
VTM: Versatile Video Coding Test Model
SPS: sequence parameter set
BDPCM: Block-based Delta Pulse Code Modulation
ACT: Adaptive Colour Transform
JEM: joint exploration model
VVC: versatile video coding
BMS: benchmark set
MV: Motion Vector
HEVC: High Efficiency Video Coding
SEI: Supplementary Enhancement Information
VUI: Video Usability Information
GOPs: Groups of Pictures
TUs: Transform Units,
PUs: Prediction Units
CTUs: Coding Tree Units
CTBs: Coding Tree Blocks
PBs: Prediction Blocks
HRD: Hypothetical Reference Decoder
SNR: Signal Noise Ratio
CPUs: Central Processing Units
GPUs: Graphics Processing Units
CRT: Cathode Ray Tube
LCD: Liquid-Crystal Display
OLED: Organic Light-Emitting Diode
CD: Compact Disc
DVD: Digital Video Disc
ROM: Read-Only Memory
RAM: Random Access Memory
ASIC: Application-Specific Integrated Circuit
PLD: Programmable Logic Device
LAN: Local Area Network
GSM: Global System for Mobile communications
LTE: Long-Term Evolution
CANBus: Controller Area Network Bus
USB: Universal Serial Bus
PCI: Peripheral Component Interconnect
FPGA: Field Programmable Gate Areas
SSD: solid-state drive
IC: Integrated Circuit
CU: Coding Unit
While this disclosure has described several exemplary embodiments,
there are alterations, permutations, and various substitute
equivalents, which fall within the scope of the disclosure. It will
thus be appreciated that those skilled in the art will be able to
devise numerous systems and methods which, although not explicitly
shown or described herein, embody the principles of the disclosure
and are thus within the spirit and scope thereof.
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